MAINTAINERS: Add maintainer for HiSilicon PTT driver

Add maintainer for driver and documentation of HiSilicon PTT device.

Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20220816114414.4092-6-yangyicong@huawei.com


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>