drm/etnaviv: mark whole context as lost in recover worker

If we reset the GPU to get it back into a usable state we lose
all context, not just the MMU one. Mark the whole context as
lost to trigger a restore of the exec and MMU state.
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>

drivers/gpu/drm/etnaviv/etnaviv_gpu.c

@@ -891,7 +891,7 @@ static void recover_worker(struct work_struct *work)
 	gpu->completed_fence = gpu->active_fence;
 
 	etnaviv_gpu_hw_init(gpu);
-	gpu->switch_context = true;
+	gpu->lastctx = NULL;
 	gpu->exec_state = -1;
 
 	mutex_unlock(&gpu->lock);