[media] go7007-loader: add support for the other devices and move fw files

Add support for the other devices that need to load the boot firmware.
All firmware files are now placed in a single go7007 directory.
Also remove the device_extension_s stuff: this is clearly a left-over from
the olden days.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>