usb: isp1760: do not sleep in field register poll

usb: isp1760: do not sleep in field register poll

When polling for a setup or clear of a register field we were sleeping
in atomic context but using a very tight sleep interval.

Since the use cases for this poll mechanism are only in setup and
stop paths, and in practice this poll is not used most of the times
but needs to be there to comply to hardware setup times, remove the
sleep time and make the poll loop tighter.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Rui Miguel Silva <rui.silva@linaro.org>
Link: https://lore.kernel.org/r/20210727100516.4190681-3-rui.silva@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>