xfs_repair: factor phase transitions into a helper

xfs_repair: factor phase transitions into a helper

Create a helper function to centralize all the stuff we do at the end of
a repair phase (which for now is limited to reporting progress).  The
next patch will add more interesting things to this helper.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>