DPI and smart shift values are not stored in the config file (MX Master 2s)

Created by: cryptomilk

I've set the DPI and the Smart Shift values but when you close solaar and then check ~/.config/solaar/config.json the values are not written to the config file.

Version: 1.0.1 https://build.opensuse.org/request/show/719864 (I've updated the openSUSE package)