LinuxKPI: 802.11: error on state transition failure

The state transition failures we were seeing in the early days are
solved. If we now experience one stop processing before passing
over to net80211 (sta_newstate()) and before updating iv_state on
the vap.

Sponsored by: The FreeBSD Foundation
Reviewed by: cc
Differential Revision: https://reviews.freebsd.org/D42423

(cherry picked from commit 45c27ad5241f5491234afd0b47d13b8005fdb4de)