sh: Add MMU dependency for kexec

Kexec is not likely to work on NON-MMU CPU because this added
depend on MMU for kexec.

Signed-off-by: Nobuhiro Iwamatsu <iwamatsu.nobuhiro@renesas.com>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index 8d50d52..19566c8 100644
--- a/arch/sh/Kconfig
+++ b/arch/sh/Kconfig
@@ -530,7 +530,7 @@
 
 config KEXEC
 	bool "kexec system call (EXPERIMENTAL)"
-	depends on SUPERH32 && EXPERIMENTAL
+	depends on SUPERH32 && EXPERIMENTAL && MMU
 	help
 	  kexec is a system call that implements the ability to shutdown your
 	  current kernel, and to start another kernel.  It is like a reboot