MAINTAINERS: add imx7d/imx6sx/imx6ul/imx8qxp and vf610 adc maintainer

Add myself as imx7d/imx6sx/imx6ul/imx8qxp and vf610 adc maintainer.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Reviewed-by: Cai Huoqing <cai.huoqing@linux.dev>
Link: https://lore.kernel.org/r/1640073000-32629-1-git-send-email-haibo.chen@nxp.com


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