media: sun6i-csi: Rename the capture video device to sun6i-csi-capture

Now that the driver is properly split between bridge and capture,
rename the video device to highlight its role and be in line with
the bridge entity naming.

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>