MAINTAINERS: use kernel.org alias

My Linaro email will stop working soon. Use @kernel.org email instead.

Signed-off-by: Dmitry Baryshkov <lumag@kernel.org>
Acked-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/641152/


Signed-off-by: Rob Clark <robdclark@chromium.org>