[Component]Fix test_get_firmware_update_notification fail#472

PJHsieh wants to merge 4 commits intosonic-net:mastersonic-net/sonic-platform-common:masterfrom

PJHsieh:Revise_get_firmware_update_notification_output_to_stringPJHsieh/sonic-platform-common:Revise_get_firmware_update_notification_output_to_stringCopy head branch name to clipboard