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: Arve Hjønnevåg <[e-mail]>
Signed-off-by: Sherry Yang <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/android/binder_alloc.c

···
 	return ret;
 }
 
-struct shrinker binder_shrinker = {
+static struct shrinker binder_shrinker = {
 	.count_objects = binder_shrink_count,
 	.scan_objects = binder_shrink_scan,
 	.seeks = DEFAULT_SEEKS,