dwc_otg: make channel halts with unknown state less damaging

If the IRQ received a channel halt interrupt through the FIQ
with no other bits set, the IRQ would not release the host
channel and never complete the URB.

Add catchall handling to treat as a transaction error and retry.
Merge pull request #340 from P33M/rpi-3.6.y

dwc_otg: make channel halts with unknown state less damaging