staging: lustre: fix return type of lo_release.

The return type of block_device_operations.release() changed to void in commit
db2a144b.

Found with the following Coccinelle patch:
<smpl>
@has_release_func@
identifier i;
identifier release_func;
@@
struct block_device_operations i = {
 .release = release_func
};

@depends on has_release_func@
identifier has_release_func.release_func;
@@
- int
+ void
release_func(...) {
...
- return ...;
}
</smpl>
Signed-off-by: Cyril Roelandt <tipecaml@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/llite/lloop.c

@@ -596,15 +596,13 @@ static int lo_open(struct block_device *bdev, fmode_t mode)
 	return 0;
 }
 
-static int lo_release(struct gendisk *disk, fmode_t mode)
+static void lo_release(struct gendisk *disk, fmode_t mode)
 {
 	struct lloop_device *lo = disk->private_data;
 
 	mutex_lock(&lo->lo_ctl_mutex);
 	--lo->lo_refcnt;
 	mutex_unlock(&lo->lo_ctl_mutex);
-
-	return 0;
 }
 
 /* lloop device node's ioctl function. */