drm: Move atomic_state_put after locks are dropped

drm_atomic_state_put doesn't require any locking, and this makes things
easier for switching to modeset_lock_all helpers in a future patch

Changes in v2:
- Moved state->acquire_ctx clear to a separate patch (Daniel)

Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20181129150423.239081-3-sean@poorly.run

drivers/gpu/drm/drm_atomic_helper.c

@@ -3294,9 +3294,9 @@ out:
 		drm_modeset_backoff(&ctx);
 	}
 
-	drm_atomic_state_put(state);
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);
+	drm_atomic_state_put(state);
 
 	return err;
 }