CUResume optimize

In intel's e100 driver, if last command to CU is transmiting(CUResume), new transmiting
command don't need to wait for previous one to finish. But in eepro100.c, function
speedo_start_xmit() wait for previous command to finish before issue CUResume to
CU.  If I call dev->hard_start_xmit() too frequently, message "Command 0000 was
not immediately accept, xxx ticks!" continually printed on screen.