kconfig: add a Memory Management options" menu

This moves all the options under a proper menu.

Based on a patch from Randy Dunlap.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/mm/Kconfig b/mm/Kconfig
index ce95491..9ae1b6a 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -1,3 +1,6 @@
+
+menu "Memory Management options"
+
 config SELECT_MEMORY_MODEL
 	def_bool y
 	depends on ARCH_SELECT_MEMORY_MODEL
@@ -762,3 +765,5 @@
 
 config ARCH_HAS_PTE_SPECIAL
 	bool
+
+endmenu