ArmPkg: Fix Ecc error 10016 in StandaloneMmMmuLib

ArmPkg: Fix Ecc error 10016 in StandaloneMmMmuLib

This patch fixes the following Ecc reported error:
Module file has FILE_GUID collision with other
module file

The two .inf files with clashing GUID are:
ArmPkg/Library/ArmMmuLib/ArmMmuBaseLib.inf
ArmPkg/Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf

As ArmMmuBaseLib.inf is older than ArmMmuStandaloneMmLib.inf,
it has precedence.

Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Reviewed-by: Sami Mujawar <sami.mujawar@arm.com>