osd/PG: fix repair_object when missing on primary

If the object is missing on the primary, we need to fully populate the
missing_loc.needs_recovery_map.  This broke with the recent refactoring of
recovery for EC, somewhere around 84e2f39c557c79e9ca7c3c3f0eb0bfa4860bf899.

Fixes: #8008
Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #1658 from ceph/wip-8008

osd: fix repair_object

Reviewed-by: Samuel Just <sam.just@inktank.com>