block: fix bad definition of BIO_RW_SYNC

We can't OR shift values, so get rid of BIO_RW_SYNC and use BIO_RW_SYNCIO
and BIO_RW_UNPLUG explicitly. This brings back the behaviour from before
213d9417fec62ef4c3675621b9364a667954d4dd.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4495104..03b4cd0 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -474,7 +474,7 @@
 	 * causes ENOTSUPP, we allocate a spare bio...
 	 */
 	struct bio *bio = bio_alloc(GFP_NOIO, 1);
-	int rw = (1<<BIO_RW) | (1<<BIO_RW_SYNC);
+	int rw = (1<<BIO_RW) | (1<<BIO_RW_SYNCIO) | (1<<BIO_RW_UNPLUG);
 
 	bio->bi_bdev = rdev->bdev;
 	bio->bi_sector = sector;
@@ -531,7 +531,7 @@
 	struct completion event;
 	int ret;
 
-	rw |= (1 << BIO_RW_SYNC);
+	rw |= (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG);
 
 	bio->bi_bdev = bdev;
 	bio->bi_sector = sector;