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/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 3b518c2..c355a95 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -40,6 +40,10 @@
 	  Enable BATs (block address translation registers) 4-7 on machines
 	  that support them.
 
+config SYS_INIT_RAM_LOCK
+	bool "Lock some portion of L1 for initial ram stack"
+	depends on MPC83xx || MPC85xx
+
 source "arch/powerpc/cpu/mpc83xx/Kconfig"
 source "arch/powerpc/cpu/mpc85xx/Kconfig"
 source "arch/powerpc/cpu/mpc8xx/Kconfig"