Convert CONFIG_ENABLE_36BIT_PHYS to Kconfig

This converts the following to Kconfig:
   CONFIG_ENABLE_36BIT_PHYS

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P2041RDB_defconfig b/configs/P2041RDB_defconfig
index 5dddbda..e6df3c8 100644
--- a/configs/P2041RDB_defconfig
+++ b/configs/P2041RDB_defconfig
@@ -8,6 +8,7 @@
 CONFIG_MPC85xx=y
 CONFIG_TARGET_P2041RDB=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
+CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_MP=y
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y