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.