Fix geolocation api setting always showing as enabled

[LAURAilway]

The radio buttons didn't correctly detect "" as a value, so the geolocation setting always appeared as "enabled" on reload, regardless of actual state. Setting the string for "disabled" to " " seems to fix the issue. I am not entirely sure if this is bad practice for whatever reason, I defer that judgement to you. Closes #3441

[LAURAilway]

Note: Setting it to about:blank (or any other non-empty string that isn't a valid url) also works, if that would be preferable for easier maintenance

[MrAlex94]

https://github.com/BrowserWorks/Waterfox/commit/4a07e9784069ce21ba99876774753e4e8d605c77