s3 onefs: Fix 1 second share mode delay handling

s3 onefs: Fix 1 second share mode delay handling

When racing to the open and loosing we may get a share_mode violation.
In this case handle the 1-second delay via a defferred open properly.

This requires us to retrieve the share_mode_lock before deferring
open so we don't dereference a NULL pointer assuming we already had
the lck because we were the first opener.