Documentation/vm/page-types.c: Declare checked_open static

Nothing outside of Documentation/vm/page-types.c references
checked_open.

Signed-off-by: Josh Triplett <[email protected]>
diff --git a/Documentation/vm/page-types.c b/Documentation/vm/page-types.c
index 3ec4f2a2..4793c6a 100644
--- a/Documentation/vm/page-types.c
+++ b/Documentation/vm/page-types.c
@@ -218,7 +218,7 @@
 	exit(EXIT_FAILURE);
 }
 
-int checked_open(const char *pathname, int flags)
+static int checked_open(const char *pathname, int flags)
 {
 	int fd = open(pathname, flags);