MAINTAINERS: Add maintainer for Analog Devices sound CODECs

The MAINTAINERS  entry for the ADI sound CODEC drivers currently only lists the
ADI devices-drivers-devel mailing-list. Add myself as additional contact, since
I'm the person at ADI who is currently doing most of the work on these drivers.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>