media: MAINTAINERS: Add myself as sun6i-csi maintainer and rename/move entry

Given the substantial rework of the driver that I carried out and the
knowledge acquired about the hardware along the way, make myself a
maintainer of the sun6i-csi driver.

Also rename and move the entry while at it since the driver is not
specific to the V3s.

Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>