Fix selection of RCUs after rename to RECVL/H

dashboards/recv.json

@@ -835,7 +835,7 @@
             "uid": "prometheus"
           },
           "exemplar": true,
-          "expr": "device_attribute{host=\"$station\",device=\"stat/(recv|rcu2l|rcu2h)/$subrack\",name=\"RECV_IOUT_error_R\"}",
+          "expr": "device_attribute{host=\"$station\",device=\"stat/(recvl|recvh)/$subrack\",name=\"RECV_IOUT_error_R\"}",
           "interval": "",
           "legendFormat": "{{x}}",
           "refId": "A"