tcp: Fix a locking issue

INP_WLOCK_RECHECK_CLEANUP() and INP_WLOCK_RECHECK() might return
from the function, so any locks held must be released.

Reported by: syzbot+b1a888df08efaa7b4bf1@syzkaller.appspotmail.com
Reviewed by: markj
Sponsored by: Netflix, Inc.
Differential Revision: https://reviews.freebsd.org/D32975