fixup! Let driver handle datetimes automatically

Author: hazzik

src/NHibernate/Driver/NpgsqlDriver.cs

@@ -82,10 +82,12 @@ protected override void InitializeParameter(DbParameter dbParam, string name, Sq
 
 		// Prior to v3, Npgsql was expecting DateTime for time.
 		// https://github.com/npgsql/npgsql/issues/347
-		public override bool RequiresTimeSpanForTime => (DriverVersion?.Major ?? 3) >= 3;
+		public override bool RequiresTimeSpanForTime => DriverVersionMajor >= 3;
 
 		public override bool HasDelayedDistributedTransactionCompletion => true;
 
 		System.Type IEmbeddedBatcherFactoryProvider.BatcherFactoryClass => typeof(GenericBatchingBatcherFactory);
+
+		private int DriverVersionMajor => DriverVersion?.Major ?? 3;
 	}
 }