blk-mq-debugfs: Declare a local symbol static

This was detected by sparse.
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/blk-mq-debugfs.c

@@ -739,7 +739,7 @@ static int blk_mq_debugfs_release(struct inode *inode, struct file *file)
 		return seq_release(inode, file);
 }
 
-const struct file_operations blk_mq_debugfs_fops = {
+static const struct file_operations blk_mq_debugfs_fops = {
 	.open		= blk_mq_debugfs_open,
 	.read		= seq_read,
 	.write		= blk_mq_debugfs_write,