feat(arm): add trusty_sp_fw_config build option

Also increase add PLAT_ARM_SP_MAX_SIZE to override the default
ARM_SP_MAX_SIZE to support Trusty image and move OPTEE_SP_FW_CONFIG
documentation to build-internals.rst as it's not externally set-able.

Signed-off-by: Arunachalam Ganapathy <arunachalam.ganapathy@arm.com>
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: Ief90ae9113d32265ee2200f35f3e517b7b9a4bea
diff --git a/docs/getting_started/build-internals.rst b/docs/getting_started/build-internals.rst
index 390c367..c43f4e9 100644
--- a/docs/getting_started/build-internals.rst
+++ b/docs/getting_started/build-internals.rst
@@ -19,3 +19,11 @@
   ``HANDLE_EA_EL3_FIRST_NS`` is set. Currently only NS world routes EA to EL3 but
   in future when Secure/Realm wants to use FFH then they can introduce new macros
   which will enable this option implicitly.
+
+-  ``OPTEE_SP_FW_CONFIG``: DTC build flag to include OP-TEE as SP in
+   tb_fw_config device tree. This flag is defined only when
+   ``ARM_SPMC_MANIFEST_DTS`` manifest file name contains pattern optee_sp.
+
+-  ``TRUSTY_SP_FW_CONFIG``: DTC build flag to include Trusty as SP in
+   tb_fw_config device tree. This flag is defined only when
+   ``ARM_SPMC_MANIFEST_DTS`` manifest file name contains pattern trusty_sp.
diff --git a/docs/getting_started/build-options.rst b/docs/getting_started/build-options.rst
index 16522bd..37545ce 100644
--- a/docs/getting_started/build-options.rst
+++ b/docs/getting_started/build-options.rst
@@ -740,10 +740,6 @@
    1 (do save and restore). 0 is the default. An SPD may set this to 1 if it
    wants the timer registers to be saved and restored.
 
--  ``OPTEE_SP_FW_CONFIG``: DTC build flag to include OP-TEE as SP in
-   tb_fw_config device tree. This flag is defined only when
-   ``ARM_SPMC_MANIFEST_DTS`` manifest file name contains pattern optee_sp.
-
 -  ``OVERRIDE_LIBC``: This option allows platforms to override the default libc
    for the BL image. It can be either 0 (include) or 1 (remove). The default
    value is 0.