Sync patch r14498 from main trunk.
Fix PciHostBridge driver to return success for EfiPciHostBridgeEndEnumeration to fix OVMF boot no display issue.

git-svn-id: svn://svn.code.sf.net/p/edk2/code/branches/UDK2010.SR1/PcAtChipsetPkg@14645 6f19259b-4bc3-4df7-8a09-765794883524