devm_gpiod_get_optional() can return an error in addition to a NULL ptr.
Check for error and propagate that to the probe function. Check return
value in probe. This will now handle EPROBE_DEFER for the reset gpio.
Signed-off-by: NPhil Reid <preid@electromag.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>