fix fp16 initializer dtype check test=develop (#15669)

python/paddle/fluid/layer_helper.py

@@ -302,7 +302,8 @@ class LayerHelper(object):
         if default_initializer is None and attr.initializer is None:
             if isinstance(dtype, core.VarDesc.VarType):
                 if dtype != core.VarDesc.VarType.FP32 and \
-                    dtype != core.VarDesc.VarType.FP64:
+                    dtype != core.VarDesc.VarType.FP64 and \
+                    dtype != core.VarDesc.VarType.FP16:
                     raise TypeError(
                         "Can not create parameter with default initializer when dtype is not float type. Set default_initializer to fit the parameter dtype!"
                     )