spmd: ensure SIMD context is saved/restored on SPMC entry/exit
spmd: ensure SIMD context is saved/restored on SPMC entry/exit

Signed-off-by: Olivier Deprez <a71d93c73db536dc855a04902dabc350f140693d@arm.com>
Change-Id: I8ed58ec5f97e05d91451020a2739464bb8e428b3

achingupta/arm-trusted-firmware,achingupta/arm-trusted-firmware