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/kmcent2_defconfig b/configs/kmcent2_defconfig
index 86c7aa5..a028c4d 100644
--- a/configs/kmcent2_defconfig
+++ b/configs/kmcent2_defconfig
@@ -8,6 +8,7 @@
 CONFIG_SYS_CLK_FREQ=66666666
 CONFIG_ENV_ADDR=0xebf20000
 CONFIG_MPC85xx=y
+CONFIG_SYS_INIT_RAM_LOCK=y
 CONFIG_TARGET_KMCENT2=y
 CONFIG_MPC85XX_HAVE_RESET_VECTOR=y
 CONFIG_ENABLE_36BIT_PHYS=y