added support for power driver setting

Change-Id: I96323cd883f2a42878fa981a487e70e5122eaefe
diff --git a/_modules/maas.py b/_modules/maas.py
index 3c9b55e..63fb098 100644
--- a/_modules/maas.py
+++ b/_modules/maas.py
@@ -365,6 +365,8 @@
             'power_type': machine_data.get('power_type', 'ipmi'),
             'power_parameters_power_address': power_data['power_address'],
         }
+        if 'power_driver' in power_data:
+            data['power_parameters_power_driver'] = power_data['power_driver']
         if 'power_user' in power_data:
             data['power_parameters_power_user'] = power_data['power_user']
         if 'power_password' in power_data: