gfs2: Initialize bio->bi_opf early

gfs2: Initialize bio->bi_opf early

Pass the right blk_opf_t value to bio_alloc() so that ->bi_ops is
initialized correctly and doesn't have to be changed later.  Adjust the
call chain to pass that value through to where it is needed (and only
there).

Add a separate blk_opf_t argument to gfs2_chain_bio() instead of copying
the value from the previous bio.

Fixes: 8a157e0a0aa5 ("gfs2: Fix use of bio_chain")
Reported-by: syzbot+f6539d4ce3f775aee0cc@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=f6539d4ce3f775aee0cc
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>