significant clean up and optimizations:
- don't call bioq_disksort() on every command, the hardware will do that for
us.
- remove all of the complicated bio deferral code. bio's that can't be
serviced immediately can just wait on the bioq.
- Only reserve one command object for doing control commands to the card.
This simplifies a lot of code and significantly reduces the size of the
command struct.
- Allocate commands out of a slab instead of embedding them into the softc.
- Call the command action method directly instead of having ips_get_free_cmd()
call it indirectly.
MFC After: 1 week
bad78b265c