Fix the typo. Field DisAutoRefresh is in DramTimngHi.

Signed-off-by: Zheng Bao <zheng.bao@amd.com>

Index: src/northbridge/amd/amdmct/mct_ddr3/mct_d.c
===================================================================
--- src/northbridge/amd/amdmct/mct_ddr3/mct_d.c	(revision 5818)
+++ src/northbridge/amd/amdmct/mct_ddr3/mct_d.c	(working copy)
@@ -1220,7 +1220,7 @@
 	Set_NB32(dev, 0x88 + reg_off, DramTimingLo);	/*DCT Timing Low*/
 
 	if (pDCTstat->Speed > 4) {
-		DramTimingLo |= 1 << DisAutoRefresh;
+		DramTimingHi |= 1 << DisAutoRefresh;
 	}
 	DramTimingHi |= 0x000018FF;
 	Set_NB32(dev, 0x8c + reg_off, DramTimingHi);	/*DCT Timing Hi*/