FPU: Added interrupts for FPU test purposes

Using timer interrupt to test FPU registers protection is not
efficient and direct. This patch involves dedicated test interrupts
respectively for NS and S, which get triggered by software (STIR)
instead of a timer. This change is applied on AN521 and Musca-S1
platforms.

Signed-off-by: Jianliang Shen <jianliang.shen@arm.com>
Change-Id: I3ce92e837fe62f94ce6fd068efedc547c5f6f3c3
28 files changed