LinuxKPI: 802.11: improve lkpi_ic_vap_delete()

Changing the order of cleanup in lkpi_ic_vap_delete() will avoid
firmware crashes or a direct panic as observed as ieee80211_vap_detach()
will do most cleanup for us and get us into the correct state.

Calling mo_stop() in lkpi_ic_vap_delete() seems to stop the problem
that further VAPs could not be created (error 17) after the first one
being destroyed.

Sponsored by: The FreeBSD Foundation
PR: 269842
Approved by: re (gjb)

(cherry picked from commit dbf7691999abe501e0ebc0fe4d8d9e97718d3890)
(cherry picked from commit 6c38c6b1b917957d420902213f318bf0153214f2)
(cherry picked from commit 53ef38313a6dd70e5d929a3d014cc62db807793f)