ppc/85xx: Simplify the top makefile for 36-bit config for P2020DS

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
diff --git a/include/configs/P2020DS.h b/include/configs/P2020DS.h
index 2a2b9ac..b48c199 100644
--- a/include/configs/P2020DS.h
+++ b/include/configs/P2020DS.h
@@ -27,6 +27,10 @@
 #ifndef __CONFIG_H
 #define __CONFIG_H
 
+#ifdef CONFIG_MK_36BIT
+#define CONFIG_PHYS_64BIT
+#endif
+
 /* High Level Configuration Options */
 #define CONFIG_BOOKE		1	/* BOOKE */
 #define CONFIG_E500		1	/* BOOKE e500 family */