ArmPkg/CpuPei: Remove unused functions from the driver

ArmPkg/CpuPei: Remove unused functions from the driver

The ConfigureMmu() function is unused - the only call to it
is commented out, and the functionality has been moved to
InitMmu() in MemoryInitPeiLib.c.
This change also removes the unused definitions from the file.

Change-Id: Ice795bfee25c403142d0c078533f8a46d04f82e9
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Roy Franz <roy.franz@linaro.org>
Signed-off-by:: Olivier Martin <olivier.martin@arm.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14621 6f19259b-4bc3-4df7-8a09-765794883524