ahc(4)/ahd(4): target mode: cancel outstanding AIOs and INOTs

When disabling a lun there can still be outstanding AIOs and INOTs, when
this happens previously the lun would just fail to disable and trying to
re-use the lun would break the card.

isp(4) in target mode does the same thing when disabling a lun, in
testing this allows re-starting of ctld(8) with connected initiators and
allows initiators to gracefully resume afterwards.

Signed-off-by: HP van Braam <hp@tmm.cx>
Reviewed by: imp, mav
Pull Request: https://github.com/freebsd/freebsd-src/pull/1190