ARM: gic: Add support for logging interrupts in RTB

To help with the debug of interrupt storms and problems during IRQ
handling, log the IRQ number in RTB for each interrupt that fires.

Change-Id: Icea5ded0f7d66ba3c7608793e7c25218e2a64e0c
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>