Remove incorrect/duplicate shape_func for where

Author: Trevor Morris

python/tvm/relay/op/_tensor.py

@@ -277,4 +277,3 @@ def elemwise_shape_func(attrs, inputs, _):
 register_shape_func("sigmoid", False, elemwise_shape_func)
 register_shape_func("isnan", False, elemwise_shape_func)
 register_shape_func("isinf", False, elemwise_shape_func)
-register_shape_func("where", False, elemwise_shape_func)