MAINTAINERS: Add Vikash as VENUS video driver co-maintainer

For the past several amendments in video driver, I have been working
with Stanimir in multiple design discussions or handling a given
issue. With this, adding myself as a co-maintainer.

Signed-off-by: Vikash Garodia <quic_vgarodia@quicinc.com>
Acked-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Acked-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>