[media] dvb-frontends/cxd2841er: make call to i2c_gate_ctrl optional

[media] dvb-frontends/cxd2841er: make call to i2c_gate_ctrl optional

Some cards/bridges wrap i2c_gate_ctrl handling with a mutex_lock(). This is
e.g. done in ddbridge to protect against concurrent tuner access with
regards to the dual tuner HW, where concurrent tuner reconfiguration can
result in tuning fails or bad reception quality. When the tuner driver
additionally tries to open the I2C gate (which e.g. the tda18212 driver
does) when the demod already did this, this will lead to a deadlock. This
makes the calls to i2c_gatectrl from the demod driver optional when the
flag is set, leaving this to the tuner driver. For readability reasons and
to not have the check duplicated multiple times, the setup is factored
into cxd2841er_tuner_set().

This commit also updates the netup card driver (which seems to be the only
consumer of the cxd2841er as of now).

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Acked-by: Abylay Ospan <aospan@netup.ru>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>