MAINTAINERS: correct file entry for AD7091R

File entry has driver/iio/adc two times. Fix the file entry

Found by ./scripts/get_maintainer.pl --self-test=patterns

Signed-off-by: Amit Dhingra <mechanicalamit@gmail.com>
Reviewed-by: Marcelo Schmitt <marcelo.schmitt1@gmail.com>
Link: https://lore.kernel.org/r/CAO=gReEUr4B+E2mQsSrncHf41f0A915SuoWgA522_2Ts-dZbSg@mail.gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>