Filter Wizard: reset both Rx/Tx caldivs when advanced is toggled

This fixes the issue where toggling advanced on one channel wouldn't
cause it to be toggled in the same fashion on the other channel.
Specifically the advanced option should be the same for both Rx/Tx
filter designs.

Signed-off-by: Tim Harder <timothy.harder@analog.com>
Filter Wizard: wipe Rx/Tx coefficients if advanced is toggled

We want to force new filter designs for both channels when advanced is
toggled.

Signed-off-by: Tim Harder <timothy.harder@analog.com>
Filter Wizard: drop unnecessary caldiv setting and add better comments

Signed-off-by: Tim Harder <timothy.harder@analog.com>