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/T2080RDB_defconfig b/configs/T2080RDB_defconfig
index 0e001e2..e43168e 100644
--- a/configs/T2080RDB_defconfig
+++ b/configs/T2080RDB_defconfig
@@ -11,6 +11,7 @@
 CONFIG_MPC85xx=y
 CONFIG_TARGET_T2080RDB=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
+CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_SYS_MEMTEST_START=0x00200000
 CONFIG_SYS_MEMTEST_END=0x00400000
 CONFIG_MP=y