azure_rm_deployment: fix rg issue with _nic_to_public_ips_instance() (#2950)

Fix an issue with _nic_to_public_ips_instance() function. There was an assumption in the code that the Public IP sits in the same resource group, this isn't always the case.

lib/ansible/modules/extras/cloud/azure/azure_rm_deployment.py

@@ -644,7 +644,7 @@ class AzureRMDeploymentManager(AzureRMModuleBase):
         return ip_dict
 
     def _nic_to_public_ips_instance(self, nics):
-        return [self.network_client.public_ip_addresses.get(self.resource_group_name, public_ip_id.split('/')[-1])
+        return [self.network_client.public_ip_addresses.get(public_ip_id.split('/')[4], public_ip_id.split('/')[-1])
                   for nic_obj in [self.network_client.network_interfaces.get(self.resource_group_name,
                                                                              nic['dep'].resource_name) for nic in nics]
                   for public_ip_id in [ip_conf_instance.public_ip_address.id