ArmPlatformPkg: Removed the check on the CpuId to release the secondary cores from...

ArmPlatformPkg: Removed the check on the CpuId to release the secondary cores from their mailbox spinning

The idea is to remove the PCD PcdGicPrimaryCoreId to make the port easier (and also to allow changing
the primary boot CPU without adding more platform specific code to UEFI).

There is a risk the mailboxes contain garbage at boot time. But it should be easy enough to clear the
mailboxes when starting UEFI to workaround this limitation.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Olivier Martin <olivier.martin@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14477 6f19259b-4bc3-4df7-8a09-765794883524