iio: adc: ad4630: Drop lower bound calibscale value check

The calibration scale value is stored in an unsigned variable so it's
value can never be a negative number. Thus, drop the lower bound check
for the calibration scale values as that is not needed.

This fixes a 'comparison of unsigned expression in '< 0' is always false'
build warn.

Signed-off-by: Marcelo Schmitt <marcelo.schmitt@analog.com>

Author: machschmitt

drivers/iio/adc/ad4630.c

@@ -606,7 +606,7 @@ static int ad4630_set_chan_gain(struct iio_dev *indio_dev, int ch,
 
 	gain = gain_int * MICRO + gain_frac;
 
-	if (gain < 0 || gain > AD4630_GAIN_MAX)
+	if (gain > AD4630_GAIN_MAX)
 		return -EINVAL;
 
 	gain = DIV_ROUND_CLOSEST_ULL(gain * 0x8000, 1000000);