radv: add a compute shader implementation for buffer to image

radv: add a compute shader implementation for buffer to image

This implements the reverse of the current buffer->image path
and can be used when we need to do image transfer on compute queues

This just adds the code turned off as we don't support separate
computes queues yet, and we don't want to use this path on the GFX
queues for DCC reasons.

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>