Add some tests for all types of SMCs

Exercise all combinations of SMCs: fast or yielding, SMC32 or SMC64
calling convention, from a 32-bit caller or a 64-bit one.

Change-Id: I6d23549818db7f1b3fd0cb4b46e5a592b04b5289
Signed-off-by: Sandrine Bailleux <sandrine.bailleux@arm.com>