qcow2: Use BDRV_SECTOR_BITS instead of its literal value

BDRV_SECTOR_BITS is defined to be 9 in block.h (and BDRV_SECTOR_SIZE
is calculated from that), but there are still a couple of places where
we are using the literal value instead of the macro.
Signed-off-by: NAlberto Garcia <berto@igalia.com>
Message-id: 20171009153856.20387-1-berto@igalia.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>

block/qcow2.c

@@ -1139,7 +1139,7 @@ static int qcow2_do_open(BlockDriverState *bs, QDict *options, int flags,
 
     s->cluster_bits = header.cluster_bits;
     s->cluster_size = 1 << s->cluster_bits;
-    s->cluster_sectors = 1 << (s->cluster_bits - 9);
+    s->cluster_sectors = 1 << (s->cluster_bits - BDRV_SECTOR_BITS);
 
     /* Initialise version 3 header fields */
     if (header.version == 2) {
@@ -1636,7 +1636,7 @@ static int64_t coroutine_fn qcow2_co_get_block_status(BlockDriverState *bs,
 
     bytes = MIN(INT_MAX, nb_sectors * BDRV_SECTOR_SIZE);
     qemu_co_mutex_lock(&s->lock);
-    ret = qcow2_get_cluster_offset(bs, sector_num << 9, &bytes,
+    ret = qcow2_get_cluster_offset(bs, sector_num << BDRV_SECTOR_BITS, &bytes,
                                    &cluster_offset);
     qemu_co_mutex_unlock(&s->lock);
     if (ret < 0) {