fix(spm-mm): tf config update to enable FP/SIMD

Per introduction of [1], update SPM-MM tf build configurations to enable
CTX_INCLUDE_FPREGS=1 to permit saving/restoring the normal world context
on world switches.
This is a security measure beyond the recommendation for SPs to
save/restore the FP/SIMD context [2].

[1] https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/15167
[2] https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/tree/services/std_svc/spm_mm/spm_mm_setup.c?h=v2.6#n186

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I7243f64799b56edcb2b19c0ca1ed0bee79288bce
3 files changed