GIC: Add API to set/clear interrupt pending

API documentation updated.

Change-Id: I14e33cfc7dfa93257c82d76fae186b17a1b6d266
Co-authored-by: Yousuf A <yousuf.sait@arm.com>
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>
10 files changed