MAINTAINERS: improve section MICROCHIP MCP3564 ADC DRIVER

Commit 33ec3e5f ("iio: adc: adding support for MCP3564 ADC") adds a new
iio driver and corresponding MAINTAINERS section. It however uses spaces
instead of a single tab for all the entries in that MAINTAINERS section.

Although, the get_maintainer.pl script handles spaces instead of tabs
silently, the MAINTAINERS will quickly get into a messy state with
different indentations throughout the file. So, the checkpatch.pl script
complains when spaces instead of a single tab are used.

Fix this recently added section using tabs instead of spaces.
Further, add the driver's ABI documentation file to this section as well.

Fixes: 33ec3e5f ("iio: adc: adding support for MCP3564 ADC")
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Link: https://lore.kernel.org/r/20231122075629.21411-1-lukas.bulwahn@gmail.com


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