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/P5040DS_SPIFLASH_defconfig b/configs/P5040DS_SPIFLASH_defconfig
index 7aa0769..054f43e 100644
--- a/configs/P5040DS_SPIFLASH_defconfig
+++ b/configs/P5040DS_SPIFLASH_defconfig
@@ -8,6 +8,7 @@
 CONFIG_MPC85xx=y
 CONFIG_TARGET_P5040DS=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
+CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_MP=y
 CONFIG_FIT=y
 CONFIG_FIT_VERBOSE=y