pf: fix pagefault in pf_getstatus()

We can't copyout() while holding a lock, in case it triggers a page
fault.
Release the lock before copyout, which is safe because we've already
copied all the data into the nvlist.

PR: 258601
Reviewed by: mjg
MFC after: 1 week
Sponsored by: Modirum MDPay
Differential Revision: https://reviews.freebsd.org/D32076

(cherry picked from commit cb13059663e455b3fc69c293dadec53c164490dc)