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>