radv: reset non-syncobj semaphore context after wait.

When I ported from libdrm, I forgot to add the line to reset
the sem, we just need to reset the context.

This fixes a regression in DOOM.

Fixes: 9ac1432a57 ("radv: port to new libdrm API.")
Reported-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/amd/vulkan/winsys/amdgpu/radv_amdgpu_cs.c

@@ -1173,6 +1173,8 @@ static int radv_amdgpu_cs_submit(struct radv_amdgpu_ctx *ctx,
 			struct drm_amdgpu_cs_chunk_dep *dep = &sem_dependencies[sem_count++];
 
 			amdgpu_cs_chunk_fence_to_dep(sem, dep);
+
+			sem->context = NULL;
 		}
 		i = num_chunks++;