vmwgfx: Hook up XV color conversion control attributes
vmwgfx: Hook up XV color conversion control attributes

This enables the standard XV color conversion control attributes
contrast, scaling, saturation and hue.

Currently the attribute change takes effect on the next image only.
If we ever implement a ReputImage callback, we can use it to update
the image immediately on attribute change.

The attribute ranges follow those used by the proprietary Nvidia driver.

Signed-off-by: Thomas Hellstrom <a26490dfbee4be3d38287ad6448444504f58193c@vmware.com>
Reviewed-by: Jakob Bornecrantz <6c68cabc7124e43c9b4d50f86510600f69e74c99@vmware.com>

dezelin/xf86-video-vmware,dezelin/xf86-video-vmware,dezelin/xf86-video-vmware