repair: cleanup helpers for tracking block usage

repair: cleanup helpers for tracking block usage

Rename get_agbno_state/set_agbno_state to get_bmap/set_bmap because
those names are more self-descriptive.  Remove the superblous mount
argument to the as the current filesystem is a global in repair.
Remove the fsbno taking variant as they just complicated the code.
Bring all uses of them into the canonical form.

Signed-off-by: Barry Naujok <bnaujok@sgi.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>