fix print function of LinearGaussian CPD
fix print function of LinearGaussian CPD

jhonatanoliveira/pgmpy,sandeepkrjha/pgmpy,ankurankan/pgmpy,pgmpy/pgmpy,pgmpy/pgmpy,khalibartan/pgmpy,sandeepkrjha/pgmpy,kris-singh/pgmpy,khalibartan/pgmpy,jhonatanoliveira/pgmpy,ankurankan/pgmpy,kris-singh/pgmpy