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/include/linux/fs.h b/include/linux/fs.h
index 6022f44..67857dc 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -87,10 +87,10 @@
 #define WRITE 1
 #define READA 2		/* read-ahead  - don't block if no resources */
 #define SWRITE 3	/* for ll_rw_block() - wait for buffer lock */
-#define READ_SYNC	(READ | (1 << BIO_RW_SYNC))
+#define READ_SYNC	(READ | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
 #define READ_META	(READ | (1 << BIO_RW_META))
-#define WRITE_SYNC	(WRITE | (1 << BIO_RW_SYNC))
-#define SWRITE_SYNC	(SWRITE | (1 << BIO_RW_SYNC))
+#define WRITE_SYNC	(WRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
+#define SWRITE_SYNC	(SWRITE | (1 << BIO_RW_SYNCIO) | (1 << BIO_RW_UNPLUG))
 #define WRITE_BARRIER	(WRITE | (1 << BIO_RW_BARRIER))
 #define DISCARD_NOBARRIER (1 << BIO_RW_DISCARD)
 #define DISCARD_BARRIER ((1 << BIO_RW_DISCARD) | (1 << BIO_RW_BARRIER))