StandaloneMmPkg/StandaloneMmCoreEntryPoint: permit the use of TE images

StandaloneMmPkg/StandaloneMmCoreEntryPoint: permit the use of TE images

TE images take up less space when using 4 KB section alignment, since
the FFS/FV generation code optimizes away the redundant, nested padding.
This saves 4 KB of space, which is a worthwhile improvement for code
that executes in place in secure context.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Achin Gupta <achin.gupta@arm.com>