SAT>IP: Add possibility to define master/slave tuners

The signal from the standard universal LNB can be split using
a simple coaxial splitter (no multiswitch) to several outputs.
In this case, the position, the polarization and low-high band
settings must be equal.

This code adds the master/slave configuration option in the
tuner settings and does the tuner arbitration to preserve
above settings.

Ideally, this arbitration and configuration may be moved to
the generic dvbs input class in future, because all dvb-s
adapters can be wired in this way, but it's more complicated.
SAT>IP: DVB-S setup - pass only set parameters