[pymtl] fixed port coloring bug in visualize
[pymtl] fixed port coloring bug in visualize

cornell-brg/pymtl,jjffryan/pymtl,tj93/pymtl,Abhinav117/pymtl,jjffryan/pymtl,jck/pymtl,tj93/pymtl,12yujim/pymtl,cornell-brg/pymtl,Abhinav117/pymtl,12yujim/pymtl,12yujim/pymtl,jjffryan/pymtl,Abhinav117/pymtl,jck/pymtl,cfelton/pymtl,Abhinav117/pymtl,Glyfina-Fernando/pymtl,cfelton/pymtl,jck/pymtl,Glyfina-Fernando/pymtl,cornell-brg/pymtl,cfelton/pymtl,Glyfina-Fernando/pymtl,tj93/pymtl