fix get_broadcast_shape for dynamic shape

mindspore/ops/_utils/utils.py

@@ -54,6 +54,8 @@ def get_broadcast_shape(x_shape, y_shape, prim_name):
             broadcast_shape_back.append(x_shape[i])
         elif x_shape[i] == y_shape[i]:
             broadcast_shape_back.append(x_shape[i])
+        elif x_shape[i] == -1 or y_shape[i] == -1:
+            broadcast_shape_back.append(-1)
         else:
             raise ValueError(f"For '{prim_name}', the x_shape {x_shape} and y_shape {y_shape} can not broadcast.")