sh: Make NUMA depend on sparsemem.

The only platforms that are supporting NUMA are doing so via
sparsemem, so update the dependency.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/mm/Kconfig b/arch/sh/mm/Kconfig
index dd9b226..c713d13 100644
--- a/arch/sh/mm/Kconfig
+++ b/arch/sh/mm/Kconfig
@@ -296,7 +296,7 @@
 
 config NUMA
 	bool "Non Uniform Memory Access (NUMA) Support"
-	depends on MMU && EXPERIMENTAL
+	depends on MMU && SPARSEMEM && EXPERIMENTAL
 	default n
 	help
 	  Some SH systems have many various memories scattered around