fix(ras): restrict RAS support for NS world

Current RAS framework in TF-A only supports handling errors originating
from NS world but the HANDLE_EA_EL3_FIRST flag configures it for all
lower Els. To make the current design of RAS explicit, rename this macro
to HANDLE_EA_EL3_FIRST_NS and set EA bit in scr_el3 only when
switching to NS world.

Note: I am unaware of any platform which traps errors originating in
Secure world to EL3, if there is any such platform then it need to
be explicitly implemented in TF-A

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: If58eb201d8fa792c16325c85c26056e9b409b750
diff --git a/plat/arm/board/tc/platform.mk b/plat/arm/board/tc/platform.mk
index a9b031d..4955479 100644
--- a/plat/arm/board/tc/platform.mk
+++ b/plat/arm/board/tc/platform.mk
@@ -21,7 +21,7 @@
 
 EL3_EXCEPTION_HANDLING	:=	0
 
-HANDLE_EA_EL3_FIRST	:=	0
+HANDLE_EA_EL3_FIRST_NS	:=	0
 
 # System coherency is managed in hardware
 HW_ASSISTED_COHERENCY	:=	1