trusty-test: Add secure timer to FP test Schedule a secure periodic timer during the FP tests so we can test that secure interrupts also preserve the FP/SIMD registers. Bug: 283822781 Change-Id: I9e1dde0a4f90056005b4593d757c52a9157ae2e1 Signed-off-by: Andrei Homescu <[email protected]>