media: MAINTAINERS: Add meson video decoder

Add an entry for the meson video decoder for amlogic SoCs.

Signed-off-by: Maxime Jourdan <mjourdan@baylibre.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>