Save Minimum Configuration saves default values for input remappings

[fatjing]

Steps:

1. Fresh install
2. Enable Settings -> Configuration -> Save Minimal Configuration
3. Remap input via Input -> RetroPad Binds or Input -> Hotkeys
4. For every key remapped, there are three more entries saved: input_*_axis, input_*_btn and input_*_mbtn. The value of them is "nul", which is the same as the default value. Seems they're not supposed to be saved