iio: chemical: bme680: change MSK->MASK in #defines

Convert all defines to use "MASK" instead of a mix of "MSK" and "MASK"

Signed-off-by: David Frey <dpfrey@gmail.com>
Reviewed-by: Himanshu Jha <himanshujha199640@gmail.com>
Tested-by: Himanshu Jha <himanshujha199640@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>