xv: change FOURCC_RGBA32 to AMD one
Initally we used value of DRM_FORMAT_ARGB8888, but it seems than xf86-video-ati has established other value for years. So, change it to well established one.
Because we define a different values, that decision breaks compilation of xf86-video-ati. I am unsure, who is right in this situation, but I guess better to use an established value, to make AMD xorg driver compile (which this PR does)
I do not aware about any of the side effects of this change (RGBA32 support in glamor XV is pretty new, and it tested only with modesetting).
Edited by Konstantin