The integrator is now parametrized through its gain and not the PI
corner frequency. The integrator gain limit is given in absolute gain
units and not relative to the proportional gain.
close#1033
Several core device drivers maintain a copy of some device state.
Since this copy is not transferred between experiments this backing state
can be different from device state when a new experiment is started.
This commit adds support for injecting initial backing state into
experiments via the device database and sets initial backing state where
known.
ad53xx (zotino): spi2 xfer_duration
novogorny: pgia gains
sampler: pgia gains, spi2 pgia and adc xfer_duration
suservo: pgia gains, spi2 pgia xfer_duration
urukul: cpld cfg (partial: rf_sw), attenuator register
spi2: div/length for xfer_duration
close#1003
