Convert CONFIG_SYS_INIT_RAM_LOCK to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_INIT_RAM_LOCK

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/P2020RDB-PC_defconfig b/configs/P2020RDB-PC_defconfig
index 5f34999..634823a 100644
--- a/configs/P2020RDB-PC_defconfig
+++ b/configs/P2020RDB-PC_defconfig
@@ -6,6 +6,7 @@
 CONFIG_DEFAULT_DEVICE_TREE="p2020rdb-pc"
 CONFIG_ENV_ADDR=0xEFF20000
 CONFIG_MPC85xx=y
+CONFIG_SYS_INIT_RAM_LOCK=y
 # CONFIG_CMD_ERRATA is not set
 CONFIG_TARGET_P2020RDB=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y