radv: free attachments on end command buffer.

If we allocate attachments in the begin command buffer due to the
render pass continue bit, we were leaking them.

Since renderpasses inside a cmd buffer malloc/free these properly,
and set to NULL, we just need to call free at end.

Fixes a memory leak with multithreading demo.

Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Cc: "17.2 17.3" <mesa-stable@lists.freedesktop.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/amd/vulkan/radv_cmd_buffer.c

@@ -2509,6 +2509,8 @@ VkResult radv_EndCommandBuffer(
 		si_emit_cache_flush(cmd_buffer);
 	}
 
+	vk_free(&cmd_buffer->pool->alloc, cmd_buffer->state.attachments);
+
 	if (!cmd_buffer->device->ws->cs_finalize(cmd_buffer->cs))
 		return VK_ERROR_OUT_OF_DEVICE_MEMORY;