packet: fix extended community parsing
packet: fix extended community parsing

Signed-off-by: ISHIDA Wataru <15703620d0b11e835ab4f34ebf88f2f40cce783e@lab.ntt.co.jp>

a16/gobgp,ramrunner/gobgp,osrg/gobgp,Dipsingh/gobgp,a16/gobgp,ishidawataru/gobgp,a16/gobgp,tamihiro/gobgp,h-naoto/gobgp,tamihiro/gobgp,j-kato/gobgp,YujiOshima/gobgp,a16/gobgp,osrg/gobgp,fujita/gobgp,ishidawataru/gobgp,osrg/gobgp,ishidawataru/gobgp,ramrunner/gobgp,fujita/gobgp,j-kato/gobgp,a16/gobgp,j-kato/gobgp,tamihiro/gobgp,tamihiro/gobgp,osrg/gobgp,fujita/gobgp,YujiOshima/gobgp,Dipsingh/gobgp,fujita/gobgp,a16/gobgp,a16/gobgp,h-naoto/gobgp,YujiOshima/gobgp,ramrunner/gobgp,Dipsingh/gobgp,h-naoto/gobgp