[media] solo6x10: move out of staging into drivers/media/pci.

Now that the custom motion detection API has been replaced with a
standard API there is no reason anymore to keep it in staging.

So (finally!) move it to drivers/media/pci.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>