ArgMaxLayer, if(out_max_val == true) should output index first and then output max value

[robotcn]

if (out_max_val)
{
    float* valptr = outptr + topk;
    for (int i=0; i<topk; i++)
    {
        **outptr[i] = vec[i].first;        ---> outptr[i] = vec[i].second
        valptr[i] = vec[i].second;    ---> valptr[i] = vec[i].first**
    }
}