Update _3gpp-nr-nrm-ecmappingrule.yang

  import _3gpp-common-top { prefix top3gpp; }

  import _3gpp-common-subnetwork { prefix subnet3gpp; }

  import _3gpp-common-managed-element { prefix me3gpp; }

  import _3gpp-nr-nrm-gnbcucpfunction {prefix gnbcucp3gpp; }

  organization "3gpp SA5";

  contact "https://www.3gpp.org/DynaReport/TSG-WG--S5--officials.htm?Itemid=464";

  }

  augment "/subnet3gpp:SubNetwork" {

    if-feature EnergyCostMapECMappingRuleUnderSubNetwork;

    if-feature ECMappingRuleUnderSubNetwork;

    uses NGRANECMappingRuleSubtree;

  }