radv: use separate bind points for the dynamic buffers

The Vulkan spec says:

   "pipelineBindPoint is a VkPipelineBindPoint indicating whether
    the descriptors will be used by graphics pipelines or compute
    pipelines. There is a separate set of bind points for each of
    graphics and compute, so binding one does not disturb the other."

CC: <mesa-stable@lists.freedesktop.org>
Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
(cherry picked from commit 7a57c827)