pieusb_usb: drop first usleep
pieusb_specific: retry inquiry after reset
pieusb_scancmd: properly return status from pieusb_cmd_get_shading_parms()
pieusb: cmdIsUnitReady -> pieusb_cmd_test_unit_ready
pieusb_specific: add comment
pieusb: cmdGetState -> pieusb_cmd_read_state
pieusb_scancmd: add comment