This also adds a newbus interface that allows a SoC to override the
following settings:
- if_dwc specific SoC initialization;
- if_dwc descriptor type;
- if_dwc MII clock.
This seems to be an old version of the hardware descriptors but it is
still in use in a few SoCs (namely Allwinner A20 and Amlogic at least).
Tested on Cubieboard2 and Banana pi.
Tested for regressions on Altera Cyclone by br@ (old version).
Obtained from: NetBSD
Previously the OACTIVE flag was being set when the tx descriptors are fully
allocated but it wasn't unset anywhere.
As soon as a packet is transmitted, unset the OACTIVE flag and call start
routine to push any pending packets from the tx queue.
This closes another race where a full tx queue would jam the tx path (tx
queue is full, new packets cannot be added to queue and dwc_txstart never
gets called).
