USB: serial: option: set driver_info for SIM5218 and compatibles

The SIMCom SIM5218 and compatible devices have 5 USB interfaces, only 4
of which are serial ports.  The fifth is a network interface supported
by the qmi-wwan driver.  Furthermore, the serial ports do not support
modem control signals.  Add driver_info flags to reflect this.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Fixes: ec0cd94d ("usb: option: add SIMCom SIM5218")
Cc: stable <stable@vger.kernel.org>	# 3.2
Signed-off-by: Johan Hovold <johan@kernel.org>