Test: Add FP interrupt test case

Add test cases for interrupt:
1. Enable secure timer interrupt in non-secure thread, check FP
   context protection after secure interrupt return to non-secure
   thread.
2. Enable non-secure timer interrupt in secure thread, check FP
   context protection after non-secure interrupt entry.

Signed-off-by: Feder Liang <Feder.Liang@arm.com>
Change-Id: I368a8ee8790f18e00a2b86644a1844e9a903aab0
8 files changed