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/qemu-ppce500_defconfig b/configs/qemu-ppce500_defconfig
index 8c7b8b4..034f7e6 100644
--- a/configs/qemu-ppce500_defconfig
+++ b/configs/qemu-ppce500_defconfig
@@ -6,6 +6,7 @@
 CONFIG_MPC85xx=y
 # CONFIG_CMD_ERRATA is not set
 CONFIG_TARGET_QEMU_PPCE500=y
+CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_SYS_MPC85XX_NO_RESETVEC=y
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y