[mpris] DesktopEntry shortcomings

[Conor Curran]

> having the extension in it would have been better for the sake of correctness.
>
> Let me rephrase: If we are to change this, let's keep it a base name,
> I think a full path would be a mistake
>
Sounds good, I was obviously loading the desktop file completely the 
wrong way.
The extension is only a small thing. So leave it as is if you like.

Thanks Mirsal,
C