net: Fix LLE lock leaks

net: Fix LLE lock leaks

Historically, lltable_try_set_entry_addr() would release the LLE lock
upon failure.  After some refactoring, it no longer does so, but
consumers were not adjusted accordingly.

Also fix a leak that can occur if lltable_calc_llheader() fails in the
ARP code, but I suspect that such a failure can only occur due to a code
bug.

Reviewed by:	bz, melifaro
Reported by:	pho
Fixes:		0b79b007ebfc ("[lltable] Restructure nd6 code.")
MFC after:	3 days
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D34831