fs: Mark function as static in fs/bio-integrity.c

Mark functions as static in bio-integrity.c because it is not used
outside this file.

This eliminates the following warnings in bio-integrity.c:
fs/bio-integrity.c:224:5: warning: no previous prototype for ‘bio_integrity_tag’ [-Wmissing-prototypes]
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Jens Axboe <axboe@fb.com>

fs/bio-integrity.c

@@ -234,7 +234,8 @@ unsigned int bio_integrity_tag_size(struct bio *bio)
 }
 EXPORT_SYMBOL(bio_integrity_tag_size);
 
-int bio_integrity_tag(struct bio *bio, void *tag_buf, unsigned int len, int set)
+static int bio_integrity_tag(struct bio *bio, void *tag_buf, unsigned int len,
+			     int set)
 {
 	struct bio_integrity_payload *bip = bio->bi_integrity;
 	struct blk_integrity *bi = bdev_get_integrity(bio->bi_bdev);