dt-bindings: iio: dac: change ad3552r maintainer

As the maintainer email no longer exists, change it to myself.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220404085000.249423-2-nuno.sa@analog.com


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