ArmPlatformPkg: Fix Ecc error 10016 in PrePi

ArmPlatformPkg: Fix Ecc error 10016 in PrePi

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:
edk2\ArmPlatformPkg\PrePi\PeiUniCore.inf
edk2\ArmPlatformPkg\PrePi\PeiMPCore.inf

Both files seem to have been imported from the previous
svn repository as the same time.

Signed-off-by: Pierre Gondois <Pierre.Gondois@arm.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>