md: use set_bit/clear_bit instead of shift/mask for bi_flags changes.

Using {set,clear}_bit is more consistent than shifting and masking.

No functional change.

Signed-off-by: NeilBrown <neilb@suse.de>

drivers/md/raid5.c

@@ -4301,7 +4301,7 @@ static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
 		rcu_read_unlock();
 		raid_bio->bi_next = (void*)rdev;
 		align_bi->bi_bdev =  rdev->bdev;
-		align_bi->bi_flags &= ~(1 << BIO_SEG_VALID);
+		__clear_bit(BIO_SEG_VALID, &align_bi->bi_flags);
 
 		if (!bio_fits_rdev(align_bi) ||
 		    is_badblock(rdev, align_bi->bi_iter.bi_sector,