Previsouly the synchronization of MpCore was using the SGI (Software
Generated Interrupt) to synchronize MpCore during the early boot.
This commit replaced this mechanism by the more appropriate SEV/WFE
instructions (Send/Wait Event instructions).
That also eases the port to a new cpu/platform.
Signed-off-by: Olivier Martin <olivier.martin@arm.com>
git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@13249 6f19259b-4bc3-4df7-8a09-765794883524