GitLab

The SMCCC, part 3 indicates that only the bottom
32-bits of a 32-bit SMC call are valid. The upper
bits must be zero. Lets enforce that so standard
service code can assume its been called that way.
Signed-off-by: Jeremy Linton <jeremy.linton@arm.com>
Change-Id: I1bac50fbdc3b6ddca5fe2d1d1f96166a65ac4eb4