RAS: Add fault injection support

The ARMv8.4 RAS extensions introduce architectural support for software
to inject faults into the system in order to test fault-handling
software. This patch introduces the build option FAULT_HANDLING_SUPPORT
to allow for lower ELs to use registers in the Standard Error Record to
inject fault. The build option RAS_EXTENSIONS must also be enabled along
with fault injection.

This feature is intended for testing purposes only, and is advisable to
keep disabled for production images.

Change-Id: I6f7a4454b15aec098f9505a10eb188c2f928f7ea
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
diff --git a/include/lib/aarch64/arch.h b/include/lib/aarch64/arch.h
index e836db1..92bb97d 100644
--- a/include/lib/aarch64/arch.h
+++ b/include/lib/aarch64/arch.h
@@ -215,6 +215,7 @@
 
 /* SCR definitions */
 #define SCR_RES1_BITS		((U(1) << 4) | (U(1) << 5))
+#define SCR_FIEN_BIT		(U(1) << 21)
 #define SCR_TWE_BIT		(U(1) << 13)
 #define SCR_TWI_BIT		(U(1) << 12)
 #define SCR_ST_BIT		(U(1) << 11)