Convert CONFIG_L2_CACHE to Kconfig

This converts the following to Kconfig:
   CONFIG_L2_CACHE

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/P1010RDB-PB_NOR_defconfig b/configs/P1010RDB-PB_NOR_defconfig
index 2e86aec..985243c 100644
--- a/configs/P1010RDB-PB_NOR_defconfig
+++ b/configs/P1010RDB-PB_NOR_defconfig
@@ -9,6 +9,7 @@
 CONFIG_SYS_INIT_RAM_LOCK=y
 CONFIG_TARGET_P1010RDB_PB=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
+CONFIG_L2_CACHE=y
 CONFIG_ENABLE_36BIT_PHYS=y
 CONFIG_SYS_MPC85XX_NO_RESETVEC=y
 CONFIG_USE_UBOOTPATH=y