netisr: Dedicated network thread is not netisr

Dedicated network thread should just fetch and run the netmsg on its
own port instead of performing full-fledged netisr operation,
e.g. run rollups

Reported-by: pavalos@
kernel - Fix incorrect assertion in nlookup()

* Fix an incorrect assertion, When ISLOCKED is set the returned ncp
  can be locked shared or exclusive in the error case, rather than
  just exclusive.
Merge branch 'master' into gsocdrm_jfree