[media] media: move dvb-usb-v2/cypress_firmware.c to media/common

Loading the cypress firmware is not dvb specific and should be common
functionality. Move the source to media/common and make it a standalone
module.
As a result we can remove the dependency on dvb-usb in go7007, which has
nothing to do with dvb.

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