(RX_RESET, TX_RESET, GLOBAL_RESET).
Commands issued while a reset is in progress may be dropped. The driver
must wait until resets are complete; ep_complete_cmd() does so.
* Change RX_RESET, TX_RESET, GLOBAL_RESET to use ep_complete_cmd().
* Revert epconfig() to use inline RX_RESET, TX_RESET.
That avoids accidentally setting IFF_UP, which breaks both diskless boot,
and "halt" commands issued before the interface is brought up.