android: binder: Change binder_shrinker to static

binder_shrinker struct is not used anywhere outside of
binder_alloc.c and should be static.
Acked-by: NArve Hjønnevåg <arve@android.com>
Signed-off-by: NSherry Yang <sherryy@android.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder_alloc.c

@@ -985,7 +985,7 @@ binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
 	return ret;
 }
 
-struct shrinker binder_shrinker = {
+static struct shrinker binder_shrinker = {
 	.count_objects = binder_shrink_count,
 	.scan_objects = binder_shrink_scan,
 	.seeks = DEFAULT_SEEKS,