Fix Dithering setting saving (at last)

[saulfabregwiivc]

This issue since the very beginning has always plagued the WiiSX family (WiiSX/-R/-RX/WiiStation), so it's time to finally get rid of this problem and finally fix it.

Added a setting in settingsRX.cfg file so Dithering can be modified manually, and will be saved and loaded correctly.

Valid values for Dithering setting (Dithering =): 0 = no dithering (None) 1 = default (by default is set to No dithering in PEOPS GPU) 2 = always use dithering (Always)

Reading your comment in your thread https://gbatemp.net/threads/wiisx-rx-a-new-fork.570252:

Quote from niuus: Original had an annoying bug with Dithering being always ON by default, even if you saved the configuration. This fixes it, benefiting with a good speedup for some games without having to always change it at boot (i.e. Castlevania: Symphony of the Night gains 16fps just on the "Select your Destiny" screen alone, your mileage may vary per scene and game).

But your fix for that was:

Correct. Even if you saved the "Off" in the GUI, it was still "On" internally when you load back the emulator, and performance takes a dip, naturally. I made it really "Off" by default.

So i was tired of that annoying bug, so i took this in my hands and made a permanent fix for Dithering setting saving. Now you can save correctly the Dithering setting, and the emulator will load your saved setting next time you startup the emu.

Cheers! @saulfabregwiivc