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/P4080DS_SDCARD_defconfig b/configs/P4080DS_SDCARD_defconfig
index dde3351..867f8aa 100644
--- a/configs/P4080DS_SDCARD_defconfig
+++ b/configs/P4080DS_SDCARD_defconfig
@@ -7,6 +7,7 @@
 CONFIG_MPC85xx=y
 CONFIG_TARGET_P4080DS=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
+CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_MP=y
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y