Reshape wrong

[Jing-Luo]

https://github.com/ZiyueHuang/MXShuffleNet/blob/master/symbol.py#L11

In shuffle operation, the code should be

data = mx.sym.reshape(data, shape=(0, -4, channels // groups, -1, -2))

For example,
(256, 60, 28, 28) should be reshaped to (256, 20, 3, 28, 28) and then we swap axes to (256, 3, 20, 28, 28) and reshape back.