For Cx, each ChipSel need to be sent MR command.

For Cx, each ChipSel need to be sent MR command.
After this patch, tilapia can run in higher memory frequency.
To test the high frequency, dont forget to change the freq limit in
mcti_d.c:
 static void mctGet_MaxLoadFreq(struct DCTStatStruc *pDCTstat)
 {
	 pDCTstat->PresetmaxFreq = 800;
 }

Signed-off-by: Zheng Bao <zheng.bao@amd.com>
Acked-by: Stefan Reinauer <stepan@coresystems.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@6276 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1