build: unify verbosity handling

This change introduces a few helper variables for dealing with verbose
and silent build modes: `silent`, `verbose`, `q` and `s`.

The `silent` and `verbose` variables are boolean values determining
whether the build system has been configured to run silently or
verbosely respectively (i.e. with `--silent` or `V=1`).

These two modes cannot be used together - if `silent` is truthy then
`verbose` is always falsy. As such:

    make --silent V=1

... results in a silent build.

In addition to these boolean variables, we also introduce two new
variables - `s` and `q` - for use in rule recipes to conditionally
suppress the output of commands.

When building silently, `s` expands to a value which disables the
command that follows, and `q` expands to a value which supppresses
echoing of the command:

    $(s)echo 'This command is neither echoed nor executed'
    $(q)echo 'This command is executed but not echoed'

When building verbosely, `s` expands to a value which disables the
command that follows, and `q` expands to nothing:

    $(s)echo 'This command is neither echoed nor executed'
    $(q)echo 'This command is executed and echoed'

In all other cases, both `s` and `q` expand to a value which suppresses
echoing of the command that follows:

    $(s)echo 'This command is executed but not echoed'
    $(q)echo 'This command is executed but not echoed'

The `s` variable is predominantly useful for `echo` commands, where you
always want to suppress echoing of the command itself, whilst `q` is
more useful for all other commands.

Change-Id: I8d8ff6ed714d3cb401946c52955887ed7dca602b
Signed-off-by: Chris Kay <chris.kay@arm.com>
diff --git a/drivers/nxp/auth/csf_hdr_parser/csf_hdr.mk b/drivers/nxp/auth/csf_hdr_parser/csf_hdr.mk
index 1af51f8..12e22e9 100644
--- a/drivers/nxp/auth/csf_hdr_parser/csf_hdr.mk
+++ b/drivers/nxp/auth/csf_hdr_parser/csf_hdr.mk
@@ -26,8 +26,8 @@
 # CST_BL31
 define CST_BL31_RULE
 $(1): $(2)
-	@echo " Generating CSF Header for $$@ $$<"
-	$(Q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
+	$(s)echo " Generating CSF Header for $$@ $$<"
+	$(q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
 					--app $(2) ${BL31_INPUT_FILE}
 endef
 
@@ -36,8 +36,8 @@
 # CST_BL32
 define CST_BL32_RULE
 $(1): $(2)
-	@echo " Generating CSF Header for $$@ $$<"
-	$(Q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
+	$(s)echo " Generating CSF Header for $$@ $$<"
+	$(q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
 					--app $(2) ${BL32_INPUT_FILE}
 endef
 
@@ -46,8 +46,8 @@
 # CST_BL33
 define CST_BL33_RULE
 $(1): $(2)
-	@echo " Generating CSF Header for $$@ $$<"
-	$(Q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
+	$(s)echo " Generating CSF Header for $$@ $$<"
+	$(q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
 					--app $(2) ${BL33_INPUT_FILE}
 endef
 
@@ -56,8 +56,8 @@
 # CST_SCP_BL2
 define CST_SCP_BL2_RULE
 $(1): $(2)
-	@echo " Generating CSF Header for $$@ $$<"
-	$(Q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
+	$(s)echo " Generating CSF Header for $$@ $$<"
+	$(q)$(CST_DIR)/create_hdr_esbc --in $(2) --out $(1) --app_off ${CSF_HDR_SZ} \
 					--app $(2) ${FUSE_INPUT_FILE}
 endef
 
diff --git a/drivers/nxp/ddr/phy-gen2/ddrphy.mk b/drivers/nxp/ddr/phy-gen2/ddrphy.mk
index ba5c774..a09a278 100644
--- a/drivers/nxp/ddr/phy-gen2/ddrphy.mk
+++ b/drivers/nxp/ddr/phy-gen2/ddrphy.mk
@@ -12,9 +12,9 @@
 DDR_PHY_H  =
 
 $(DDR_PHY_C): $(DDR_PHY_H) $(COMMON_HDRS) src
-	@cp -r "$(DDR_PHY_PATH)/$@" "$(SRC_DIR)/$@"
+	$(q)cp -r "$(DDR_PHY_PATH)/$@" "$(SRC_DIR)/$@"
 
 $(DDR_PHY_H): src
-	@cp -r "$(DDR_PHY_PATH)/$@" "$(SRC_DIR)/$@"
+	$(q)cp -r "$(DDR_PHY_PATH)/$@" "$(SRC_DIR)/$@"
 
 #------------------------------------------------