media: dvb-usb: Add memory free on error path in dw2102_probe()

If dw2102_probe() fails on dvb_usb_device_init(), then memleak occurs.

The patch adds deallocation to the error path.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Anton Vasilyev <vasilyev@ispras.ru>
Reviewed-by: Enrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>