StandaloneMmPkg: Enforce alignment check for AArch64

StandaloneMmPkg: Enforce alignment check for AArch64

On AArch64, Standalone MM during the SEC phase runs in S-EL0 with
SCTLR_EL1.A=1. This patch adds the -mstrict-align compiler flag to
ensure that the generated code is compliant with the runtime
alignment checks.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Signed-off-by: Sughosh Ganu <sughosh.ganu@arm.com>
Reviewed-by: Achin Gupta <achin.gupta@arm.com>