mm/Kconfig: fix trivial help text punctuation

End a Kconfig help text sentence with a period (aka full stop).

Link: http://lkml.kernel.org/r/c17f2c75-dc2a-42a4-2229-bb6b489addf2@infradead.orgSigned-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/Kconfig

@@ -29,7 +29,7 @@ config FLATMEM_MANUAL
 
 	  For systems that have holes in their physical address
 	  spaces and for features like NUMA and memory hotplug,
-	  choose "Sparse Memory"
+	  choose "Sparse Memory".
 
 	  If unsure, choose this option (Flat Memory) over any other.