iio: adc: mp2629: fix wrong comparison of channel

Input voltage channel enum is compared against iio address instead
of the channel.

Fixes: 7abd9fb64682 ("iio: adc: mp2629: Add support for mp2629 ADC driver")
Signed-off-by: Saravanan Sekar <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Cc: <[e-mail]>
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/mp2629_adc.c

···
 		if (ret)
 			return ret;
 
-		if (chan->address == MP2629_INPUT_VOLT)
+		if (chan->channel == MP2629_INPUT_VOLT)
 			rval &= GENMASK(6, 0);
 		*val = rval;
 		return IIO_VAL_INT;