[Distributed] fix TypeError of multi learning_rate input.

Signed-off-by: 泊霆 <hujunqi.hjq@alibaba-inc.com>

tensorflow/python/distribute/hvd_strategy.py

@@ -388,10 +388,9 @@ def wraps_optimizer(cls):
       HvdOptimizer
     '''
     class HvdOptimizer(cls, optimizer.Optimizer):
-        def __init__(self, *args, **kwargs):
-            kwargs["learning_rate"] = kwargs.get("learning_rate", 0.001) *\
-                                                 HvdContext.get().world_size
-            super(HvdOptimizer, self).__init__(*args, **kwargs)
+        def __init__(self, learning_rate=0.001, *args, **kwargs):
+            learning_rate = learning_rate * HvdContext.get().world_size
+            super(HvdOptimizer, self).__init__(learning_rate, *args, **kwargs)
 
         def compute_gradients(self, loss, **kwargs):
             loss = hvd.allreduce(loss, op=hvd.Sum)
@@ -1449,4 +1448,4 @@ def export(export_dir_base,
                       as_text=as_text,
                       clear_devices=clear_devices,
                       strip_default_attrs=strip_default_attrs,
-                      modes=[mode])
+                      modes=[mode])