BeagleBoardPkg: clone MemoryInitPeiLib

BeagleBoardPkg: clone MemoryInitPeiLib

The common MemoryInitPeiLib implementation preserves the primary FV
holding the PrePi module and the compressed secondary FV, and removes
the memory it occupies from the memory map, hiding it from the OS.

The only platform that actual requires this is BeagleBoardPkg, since
it exposes the PeCoff and LZMA libraries in PrePi to DXE core via
special HOBs. So let's give BeagleBoard its own MemoryInitPeiLib, so
that we can clean up the generic version.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>