ArmPkg/AArch64Mmu: remove cache maintenance for page tables

ArmPkg/AArch64Mmu: remove cache maintenance for page tables

All our page tables are allocated from memory whose cacheability
attributes are inherited by the cacheability bits in the MMU control
register, so there is no need for explicit cache maintenance after
updating the page tables. And even if there were, Set/Way operations
are not appropriate anyway for ensuring that these changes make it to
main memory. So just remove the explicit cache maintenance completely.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18570 6f19259b-4bc3-4df7-8a09-765794883524