* Expose a couple more register access routines
* The linux driver just has a 16 bit little endian field named
  'sequence' in the driver; the openbsd driver breaks it out
  into a struct.  I'm going with the Linux structs so I'm going
  with the Linux way - so add some accessor macros to that field.
Add in a prototype for receive handling.

iwa_notif_intr() is from the openbsd driver, changed to work on freebsd.
Most of the commands are currently stubbed out, but the firmware completion
notification is in there.

This works enough to finish injecting the firmware into the chip and get
the MVM notification saying that the firmware load completed.

Next up - NVM (NVRAM/EEPROM) loading!