Fixup direct bi_rw modifiers

bi_rw should be using bio_set_op_attrs to set bi_rw.

Signed-off-by: Shaun Tancheff <shaun@tancheff.com>
Cc: Chris Mason <clm@fb.com>
Cc: Josef Bacik <jbacik@fb.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Mike Christie <mchristi@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>