iio: adc: ad7780: Add parentheses to macros

- Fix CHECK Macro argument 'wordsize' may be better as '(wordsize)' to avoid precedence issues

Slightly modified by Jonathan to take into account the staging graduation
and a copy and paste version of the same item on the following line.

Signed-off-by: Vladimir Petrigo <vladimir.petrigo@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7780.c

@@ -206,9 +206,9 @@ static const struct ad_sigma_delta_info ad7780_sigma_delta_info = {
 };
 
 #define AD7780_CHANNEL(bits, wordsize) \
-	AD_SD_CHANNEL(1, 0, 0, bits, 32, wordsize - bits)
+	AD_SD_CHANNEL(1, 0, 0, bits, 32, (wordsize) - (bits))
 #define AD7170_CHANNEL(bits, wordsize) \
-	AD_SD_CHANNEL_NO_SAMP_FREQ(1, 0, 0, bits, 32, wordsize - bits)
+	AD_SD_CHANNEL_NO_SAMP_FREQ(1, 0, 0, bits, 32, (wordsize) - (bits))
 
 static const struct ad7780_chip_info ad7780_chip_info_tbl[] = {
 	[ID_AD7170] = {