ArmPkg/PeiServicesTablePointerLib: add missing MigratePeiServicesTablePointer()

ArmPkg/PeiServicesTablePointerLib: add missing MigratePeiServicesTablePointer()

As of SVN 15115, the PEI core needs a MigratePeiServicesTablePointer function.

Background: The ArmPkg variant of the PeiServicesTablePointerLib implements
the standard PEI Services table retrieval mechanism as defined in the
PI Specification Volume 1 section 5.4.4 using the TPIDRURW registers.
No special action is required on ARM to migrate the PEI Services table
pointer after main memory initialization but a function must be implemented
nonetheless.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Eugene Cohen <eugene@hp.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18953 6f19259b-4bc3-4df7-8a09-765794883524