Convert CONFIG_SYS_RAMBOOT to Kconfig

This converts the following to Kconfig:
   CONFIG_SYS_RAMBOOT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/powerpc/cpu/mpc85xx/Kconfig b/arch/powerpc/cpu/mpc85xx/Kconfig
index f4f5ebf..9c5b1af 100644
--- a/arch/powerpc/cpu/mpc85xx/Kconfig
+++ b/arch/powerpc/cpu/mpc85xx/Kconfig
@@ -109,6 +109,7 @@
 	bool "Support qemu-ppce500"
 	select ARCH_QEMU_E500
 	select PHYS_64BIT
+	select SYS_RAMBOOT
 	imply OF_HAS_PRIOR_STAGE
 
 config TARGET_T1024RDB