Use the `use_polling' hack to make sure usb_delay_ms() will not call tsleep(9) on resume.  deraadt@ pointed that this not needed for powerdown since `cold' is set.
Use the `use_polling' hack to make sure usb_delay_ms() will not
call tsleep(9) on resume.  deraadt@ pointed that this not needed
for powerdown since `cold' is set.

Another approach would be to call delay() directly in the reset
functions, but let stay coherent with the other HC drivers.

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars