media: MAINTAINERS: Change Todor Tomov's email address

My Linaro email address with be inactive very soon so switch
it to my Gmail address.

Signed-off-by: Todor Tomov <todor.tomov@linaro.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>