解决6254使用ec20，偶发性无法注册wwan0节点的问题

使用 GobiNet or QMI WWAN，需要阻止第四个接口注册为串口。

kernel/drivers/usb/serial/option.c

/*

 * Allow matching on bNumEndpoints for devices whose inte**ce numbers

 * can change (e.g. Quectel EP06).

 */

if (device_flags & NUMEP2 && iface_desc->bNumEndpoints != 2)

return -ENODEV;

#if 1  //Added by Sky

//Quectel UC20's inte**ce 4 can be used as USB Network device  

if (serial->dev->descriptor.idVendor == cpu_to_le16(0x05C6) && serial->dev->descriptor.idProduct == cpu_to_le16(0x9003)  \

 && serial->inte**ce->cur_altsetting->desc.bInte**ceNumber >= 4)   

return -ENODEV;

//Quectel EC20's inte**ce 4 can be used as USB Network device  

if (serial->dev->descriptor.idVendor == cpu_to_le16(0x05C6) && serial->dev->descriptor.idProduct == cpu_to_le16(0x9215)  \

&& serial->inte**ce->cur_altsetting->desc.bInte**ceNumber >= 4)   

return -ENODEV;

//Quectel EC21&EC25&EC20 R2.0's inte**ce 4 can be used as USB Network device  

if (serial->dev->descriptor.idVendor == cpu_to_le16(0x2C7C)   \

&& serial->inte**ce->cur_altsetting->desc.bInte**ceNumber >= 4)   

return -ENODEV;

#endif

/* Store the device flags so we can use them during attach. */

usb_set_serial_data(serial, (void *)device_flags);