media: v4l2-pci-skeleton: Rename second ioctl handlers argument to 'void *priv'

media: v4l2-pci-skeleton: Rename second ioctl handlers argument to 'void *priv'

The second argument to the ioctl handlers is not a file handle any more.
Rename it to 'void *priv', to avoid misconceptions. This is particularly
important in the v4l2-pci-skeleton driver, as it is meant to be a base
for new drivers.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>