Stop using immap_t for guts offset on 85xx

In the future the offsets to various blocks may not be in same location.
Move to using CFG_MPC85xx_GUTS_ADDR as the base of the guts registers
instead of getting it via &immap->im_gur.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/board/stxssa/stxssa.c b/board/stxssa/stxssa.c
index 9bacb98..253fb2b 100644
--- a/board/stxssa/stxssa.c
+++ b/board/stxssa/stxssa.c
@@ -302,8 +302,7 @@
 
 #if defined(CONFIG_DDR_DLL)
 	{
-		volatile immap_t *immap = (immap_t *)CFG_IMMR;
-		volatile ccsr_gur_t *gur= &immap->im_gur;
+		volatile ccsr_gur_t *gur = (void *)(CFG_MPC85xx_GUTS_ADDR);
 		uint temp_ddrdll = 0;
 
 		/* Work around to stabilize DDR DLL */