Implementing enable_ms is optional by serial_core.
check_modem_status is just an empty local function.
Signed-off-by: NNiklas Cassel <nks@flawful.org>
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>
Tested-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>