radv: handle primitive id input into fragment shader with no geom shader

radv: handle primitive id input into fragment shader with no geom shader

Fixes:
dEQP-VK.pipeline.framebuffer_attachment.no_attachments
dEQP-VK.pipeline.framebuffer_attachment.no_attachments_ms

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Signed-off-by: Dave Airlie <airlied@redhat.com>