media: dvb-frontends: Remove redundant error check on variable ret

An earlier commit removed a call to lgdt3306a_spectral_inversion and
omitted to remove the error return check. The check on ret is now
redundant and can be removed.

Addresses-Coverity: ("Logically dead code")

Fixes: d4a3fa66 ("media: dvb-frontends: lgdt3306a.c: remove dead code")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>