CFT: Update to xf86-video-ati 7.5.0

[Warren Block]

On Mon, 27 Oct 2014, Jean-Sébastien Pédron wrote:

> Before updating xf86-video-ati to 7.5.0, we would like some people to
> try it out. The reason is that 7.4.0 was crashing for several users, so
> we want to be sure it's fixed in 7.5.0.

Additional tests.  All of these worked:

Radeon HD 6550D (AMD A8-3850 APU)
Radeon X300 PCIe
Radeon HD 4350 PCIe