GM: make loopback updated check more explicit
GM: make loopback updated check more explicit

This previously checked if parser_pyx filled the defaultdict, now it checks the values in the list (same either way)

commaai/openpilot,commaai/openpilot,commaai/openpilot,commaai/openpilot,commaai/openpilot,commaai/openpilot