media: dvb-frontends: rtl2832_sdr: set error code in probe

If rtl2832_sdr_probe() encounters an unsupported tuner it cleans up
everything and returns 0. This can result in various bad things later.
The patch sets the error code on the corresponding path.

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

Signed-off-by: Evgeny Novikov <novikov@ispras.ru>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>