nd6_llinfo_timer() functions with a KASSERT().
Note: there is no need to return after panic.
In the legacy IP case, only assign the arg after the check,
in the IPv6 case, remove the extra checks for the table and
interface as they have to be there unless we freed and forgot
to cancel the timer. It doesn't matter anyway as we would
panic on the NULL pointer deref immediately and the bug is
elsewhere.
This unifies the code of both address families to some extend.
Reviewed by: rwatson
MFC after: 6 days
19291ab3de