Fuck this. Get the newest Radeon drivers. (not for mobility, but regular)
And then modify them either manually or that Driverheaven mobilty tool.
That's how I keep my laptop drivers up to date.
Some manufacturers restricted their driver support or something like that, can't find the right page right now. Maybe someone else will give proper reason for this.
i5 6600k @ 4.3 GHz | MSI z170 Gaming M7 | 32GB Kingston HyperX Fury | 850 Evo 500GB | EVGA 1070 SC | Seasonic X-660 | CM Storm Stryker