ICNR init of `x`, with `scale` and `init` function.

def icnr(x, scale=2, init=nn.init.kaiming_normal_):
    "ICNR init of `x`, with `scale` and `init` function."
    ni,nf,h,w = x.shape
    ni2 = int(ni/(scale**2))
    k = init(torch.zeros([ni2,nf,h,w])).transpose(0, 1)
    k = k.contiguous().view(ni2, nf, -1)
    k = k.repeat(1, 1, scale**2)
    k = k.contiguous().view([nf,ni,h,w]).transpose(0, 1)
    x.data.copy_(k)