If PIIX4 Power Management Base Address (PMBA) is already programmed, then read and use it's current setting. Signed-off-by: Andrei Warkentin <andreiw@motorola.com> Reviewed-by: gavinguan Signed-off-by: jljusten git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12053 6f19259b-4bc3-4df7-8a09-765794883524