bcache: remove unnecessary space before ioctl function pointer arguments

This is warned by checkpatch.pl, this patch removes the extra space.
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Shenghui Wang <shhuiw@foxmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/md/bcache/bcache.h

@@ -275,7 +275,7 @@ struct bcache_device {
 
 	int (*cache_miss)(struct btree *b, struct search *s,
 			  struct bio *bio, unsigned int sectors);
-	int (*ioctl) (struct bcache_device *d, fmode_t mode,
+	int (*ioctl)(struct bcache_device *d, fmode_t mode,
 		     unsigned int cmd, unsigned long arg);
 };