FPU: Change interrupt test cases

Using timer interrupt to test FPU registers protection is not efficient
and direct. This patch refine test cases about FPU interrupt protection.

1. In secure, case 3 triggers a secure interrupt in secure client to
   test both caller and callee registers protection.
2. In non-secure, case 3 triggers a non-secure interrupt in non-secure
   client to test caller registers protection.
3. In non-secure, case 4 calls psa_call to enter secure world and then
   secure service triggers a non-secure interrupt to test caller
   and callee registers protection.

Signed-off-by: Jianliang Shen <jianliang.shen@arm.com>
Change-Id: I17d4f5d63c282d78db58ed57cea5b0d1f3b0da65
7 files changed