feat: unify Firmware First handling of lower el EA

Lower EL External Abort tests were implemented in such a way that after
triggering EA in tftf it gets trapped in EL3 and causing a crash in EL3
Because of the tests ending up in crash there are few problems:
 - Need to have to seperate tests one each for sync EA and Serror.
 - Unable to test the behaviour of system had the lower EL EA's been
   properly handled in EL3.

This patch merges both lower EL injection tests in single test suite and
expects a proper handling of lower EL EA's in TF-A. TF-A build macro
PLATFORM_TEST_EA_FFH allows fvp to have a proper handling.

This change will prepare ground for testing EA's which are caused by
syncronization barriers at exception boundry, which needs proper
handling of EA and then continue handling the original exception.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I27d6a3d63ec4fc873ce07a55452185b6b6b4281a
8 files changed