patch: update iwi(4)

[Johannes Hofmann]

Hi,

http://leaf.dragonflybsd.org/~hofmann/iwi_update.diff
is a patch to bring in the newest iwi(4) from FreeBSD.
It basically works and I can associate via wpa2.
There are some issues though that need to be resolved:

* Locking is done completely with lockmgr locks as it is done for
  ath now. What is the plan about if_serializer?
  I noticed that e.g. parent_updown() in ieee80211_proto.c calls
  if_ioctl without if_serializer held. Does this mean that
  if_serializer use is deprecated?

* It still uses our old firmware API via wrapper functions, as I
  didn't know how to create the firmware modules needed with the new API.
  Therefore the patch brings kern_firmware.c back into the kernel
  build, but all this can easily be switched to the new API.

* sysctl's are not removed on module unload, so when unloading/loading
  I get warnings about reusing sysctl leafs. I didn't find the
  relevent code in the other drivers, so maybe I'm missing something
  here.

* The alloc_unr()/free_unr() stuff is just commented out. Are there
  any plans to bring in this API from FreeBSD?