Make cpu operations warning a VERBOSE print

The assembler helper function `print_revision_warning` is used when a
CPU specific operation is enabled in the debug build (e.g. an errata
workaround) but doesn't apply to the executing CPU's revision/part number.
However, in some cases the system integrator may want a single binary to
support multiple platforms with different IP versions, only some of which
contain a specific erratum.  In this case, the warning can be emitted very
frequently when CPUs are being powered on/off.

This patch modifies this warning print behaviour so that it is emitted only
when LOG_LEVEL >= LOG_LEVEL_VERBOSE. The `debug.h` header file now contains
guard macros so that it can be included in assembly code.

Change-Id: Ic6e7a07f128dcdb8498a5bfdae920a8feeea1345
diff --git a/lib/cpus/aarch64/cpu_helpers.S b/lib/cpus/aarch64/cpu_helpers.S
index e41d95b..dab933c 100644
--- a/lib/cpus/aarch64/cpu_helpers.S
+++ b/lib/cpus/aarch64/cpu_helpers.S
@@ -35,6 +35,7 @@
 #if IMAGE_BL31
 #include <cpu_data.h>
 #endif
+#include <debug.h>
 
  /* Reset fn is needed in BL at reset vector */
 #if IMAGE_BL1 || IMAGE_BL31
@@ -204,10 +205,10 @@
 	ret
 endfunc get_cpu_ops_ptr
 
-#if DEBUG
-.section .rodata.rev_warn_str, "aS"
-rev_warn_str:
-	.asciz "Warning: Skipping CPU specific reset operation for non-matching CPU revision number.\n"
+#if LOG_LEVEL >= LOG_LEVEL_VERBOSE
+.section .rodata.rev_verbose_str, "aS"
+rev_verbose_str:
+	.asciz "VERBOSE: Skipping CPU specific reset operation for non-matching CPU revision number.\n"
 
 	/*
 	 * This function prints the above warning message to the crash console.
@@ -224,7 +225,7 @@
 	/* Check if the console is initialized */
 	cbz	x0, 1f
 	/* The console is initialized */
-	adr	x4, rev_warn_str
+	adr	x4, rev_verbose_str
 	bl	asm_print_str
 1:
 	ret	x5