V4L/DVB (13554a): v4l: Use the video_drvdata function in drivers

Fix all device drivers to use the video_drvdata function instead of
maintaining a local list of minor to private data mappings. Call
video_set_drvdata to register the driver private pointer when not
already done.

Where applicable, the local list of mappings is completely removed when
it becomes unused.

[mchehab.redhat.com: patch broke into two. This one changes just tm6000]

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>