85xx/86xx: Rename ext_refrec to timing_cfg_3 to match docs

All the 85xx and 86xx UM describe the register as timing_cfg_3
not as ext_refrec.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/include/configs/sbc8641d.h b/include/configs/sbc8641d.h
index 18cedff..20da73e 100644
--- a/include/configs/sbc8641d.h
+++ b/include/configs/sbc8641d.h
@@ -136,7 +136,7 @@
     #define CFG_DDR_CS1_CONFIG	0x00000000
     #define CFG_DDR_CS2_CONFIG	0x00000000
     #define CFG_DDR_CS3_CONFIG	0x00000000
-    #define CFG_DDR_EXT_REFRESH 0x00000000
+    #define CFG_DDR_TIMING_3 0x00000000
     #define CFG_DDR_TIMING_0	0x00220802
     #define CFG_DDR_TIMING_1	0x38377322
     #define CFG_DDR_TIMING_2	0x002040c7