refactor(ras): replace RAS_EXTENSION with FEAT_RAS

The current usage of RAS_EXTENSION in TF-A codebase is to cater for two
things in TF-A :
1. Pull in necessary framework and platform hooks for Firmware first
   handling(FFH) of RAS errors.
2. Manage the FEAT_RAS extension when switching the worlds.

FFH means that all the EAs from NS are trapped in EL3 first and signaled
to NS world later after the first handling is done in firmware. There is
an alternate way of handling RAS errors viz Kernel First handling(KFH).
Tying FEAT_RAS to RAS_EXTENSION build flag was not correct as the
feature is needed for proper handling KFH in as well.

This patch breaks down the RAS_EXTENSION flag into a flag to denote the
CPU architecture `ENABLE_FEAT_RAS` which is used in context management
during world switch and another flag `RAS_FFH_SUPPORT` to pull in
required framework and platform hooks for FFH.

Proper support for KFH will be added in future patches.

BREAKING CHANGE: The previous RAS_EXTENSION is now deprecated. The
equivalent functionality can be achieved by the following
2 options:
 - ENABLE_FEAT_RAS
 - RAS_FFH_SUPPORT

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I1abb9ab6622b8f1b15712b12f17612804d48a6ec
diff --git a/bl31/aarch64/ea_delegate.S b/bl31/aarch64/ea_delegate.S
index 9419476..5d2534b 100644
--- a/bl31/aarch64/ea_delegate.S
+++ b/bl31/aarch64/ea_delegate.S
@@ -153,7 +153,7 @@
  * x1: EA syndrome
  */
 func delegate_sync_ea
-#if RAS_EXTENSION
+#if RAS_FFH_SUPPORT
 	/*
 	 * Check for Uncontainable error type. If so, route to the platform
 	 * fatal error handler rather than the generic EA one.
@@ -183,7 +183,7 @@
  * x1: EA syndrome
  */
 func delegate_async_ea
-#if RAS_EXTENSION
+#if RAS_FFH_SUPPORT
 	/* Check Exception Class to ensure SError, as this function should
 	 * only be invoked for SError. If that is not the case, which implies
 	 * either an HW error or programming error, panic.
diff --git a/bl31/aarch64/runtime_exceptions.S b/bl31/aarch64/runtime_exceptions.S
index 2fa9f06..a41737a 100644
--- a/bl31/aarch64/runtime_exceptions.S
+++ b/bl31/aarch64/runtime_exceptions.S
@@ -50,16 +50,16 @@
 	/*
 	 * Macro that prepares entry to EL3 upon taking an exception.
 	 *
-	 * With RAS_EXTENSION, this macro synchronizes pending errors with an ESB
-	 * instruction. When an error is thus synchronized, the handling is
+	 * With RAS_FFH_SUPPORT, this macro synchronizes pending errors with an
+	 * ESB instruction. When an error is thus synchronized, the handling is
 	 * delegated to platform EA handler.
 	 *
-	 * Without RAS_EXTENSION, this macro synchronizes pending errors using
+	 * Without RAS_FFH_SUPPORT, this macro synchronizes pending errors using
 	 * a DSB, unmasks Asynchronous External Aborts and saves X30 before
 	 * setting the flag CTX_IS_IN_EL3.
 	 */
 	.macro check_and_unmask_ea
-#if RAS_EXTENSION
+#if RAS_FFH_SUPPORT
 	/* Synchronize pending External Aborts */
 	esb
 
@@ -307,7 +307,7 @@
 end_vector_entry fiq_sp_elx
 
 vector_entry serror_sp_elx
-#if !RAS_EXTENSION
+#if !RAS_FFH_SUPPORT
 	/*
 	 * This will trigger if the exception was taken due to SError in EL3 or
 	 * because of pending asynchronous external aborts from lower EL that got
@@ -359,7 +359,7 @@
 vector_entry serror_aarch64
 	save_x30
 	apply_at_speculative_wa
-#if RAS_EXTENSION
+#if RAS_FFH_SUPPORT
 	msr	daifclr, #DAIF_ABT_BIT
 #else
 	check_and_unmask_ea
@@ -402,7 +402,7 @@
 vector_entry serror_aarch32
 	save_x30
 	apply_at_speculative_wa
-#if RAS_EXTENSION
+#if RAS_FFH_SUPPORT
 	msr	daifclr, #DAIF_ABT_BIT
 #else
 	check_and_unmask_ea