media: MAINTAINERS: Update Benjamin Gaignard maintainer status

Update Benjamin Gaignard address and remove it from no more maintained
drivers.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Philippe Cornu <philippe.cornu@foss.st.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>