linux-wandboard

[media] dvb_usb_v2: use container_of() for adapter to device

We dont need that pointer as we can use container_of() macro thus
remove it.

Signed-off-by: Antti Palosaari <crope@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>