spd: trusty : fix defects flagged by MISRA scan
Main Fixes:
Use int32_t replace int [Rule 4.6]
Added explicit casts (e.g. 0U) to integers in order for them to be
compatible with whatever operation they're used in [Rule 10.1]
Force operands of an operator to the same type category [Rule 10.4]
Fixed if statement conditional to be essentially boolean [Rule 14.4]
Voided non c-library functions whose return types are not used
[Rule 17.7]
Change-Id: I98caa330c371757eb2dfb9438448cb99115ed907
Signed-off-by: Anthony Zhou <anzhou@nvidia.com>