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

The PGA gain value is stored in an unsigned variable so it's value can
never be a negative number. Thus, drop the lower bound check for PGA gain
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 <[email protected]>

Author: machschmitt

drivers/iio/adc/ad4630.c

@@ -554,7 +554,7 @@ static int ad4630_calc_pga_gain(int gain_int, int gain_fract, int vref,
 
 	gain_nano = gain_int * NANO + gain_fract;
 
-	if (gain_nano < 0 || gain_nano > ADAQ4224_GAIN_MAX_NANO)
+	if (gain_nano > ADAQ4224_GAIN_MAX_NANO)
 		return -EINVAL;
 
 	tmp = DIV_ROUND_CLOSEST_ULL(gain_nano << precision, NANO);