bcachefs: refactor pin put helpers

bcachefs: refactor pin put helpers

We have a couple journal pin put helpers to handle cases where the
journal lock is already held or not. Refactor the helpers to lock
and reclaim from the highest level and open code the reclaim from
the one caller of the internal variant. The latter call will be
moved into the journal buf release helper in a later patch.

Signed-off-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>