usb: xhci: Better error handling in abort_td()

If the xHC has a problem with our STOP ENDPOINT command, it is likely to
return a completion directly instead of first a transfer event for the
in-progress transfer. Handle that more gracefully.

We still BUG() on the error code, but at least we don't end up timing
out on the event and ending up with unexpected event errors.

Signed-off-by: Hector Martin <marcan@marcan.st>
Reviewed-by: Marek Vasut <marex@denx.de>