media: MAINTAINERS: Add entry for the Allwinner A31 MIPI CSI-2 bridge driver

Add myself as maintainer of the Allwinner A31 MIPI CSI-2 bridge media
driver.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>