gv_stream: avoid a crash in case of a data gvsp packet with packet_id = 0.
gv_stream: avoid a crash in case of a data gvsp packet with packet_id = 0.

lu-zero/aravis,lu-zero/aravis,lu-zero/aravis,AnilRamachandran/aravis,AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis,AravisProject/aravis,lu-zero/aravis,AnilRamachandran/aravis,lu-zero/aravis,AnilRamachandran/aravis,AravisProject/aravis,AravisProject/aravis,AnilRamachandran/aravis