USB: serial: mos7840: add a product ID for the new product

Add a new PID 0x7843 to the driver.
Let the new products be able to set up 3 serial ports with the driver.

Note that this depends on e8603076f540 ("USB: serial: mos7840: clean up
register handling").

Signed-off-by: JackyChou <[e-mail]>
[ johan: mention dependency in case anyone wants to backport this ]
Signed-off-by: Johan Hovold <[e-mail]>

drivers/usb/serial/mos7840.c

···
 /* The native mos7840/7820 component */
 #define USB_VENDOR_ID_MOSCHIP           0x9710
 #define MOSCHIP_DEVICE_ID_7840          0x7840
+#define MOSCHIP_DEVICE_ID_7843          0x7843
 #define MOSCHIP_DEVICE_ID_7820          0x7820
 #define MOSCHIP_DEVICE_ID_7810          0x7810
 /* The native component can have its vendor/device id's overridden
···
 
 static const struct usb_device_id id_table[] = {
 	{USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7840)},
+	{USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7843)},
 	{USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7820)},
 	{USB_DEVICE(USB_VENDOR_ID_MOSCHIP, MOSCHIP_DEVICE_ID_7810)},
 	{USB_DEVICE(USB_VENDOR_ID_BANDB, BANDB_DEVICE_ID_USO9ML2_2)},
···
 	int device_type;
 
 	if (product == MOSCHIP_DEVICE_ID_7810 ||
-		product == MOSCHIP_DEVICE_ID_7820) {
+		product == MOSCHIP_DEVICE_ID_7820 ||
+		product == MOSCHIP_DEVICE_ID_7843) {
 		device_type = product;
 		goto out;
 	}
···
 	int device_type = (unsigned long)usb_get_serial_data(serial);
 	int num_ports;
 
-	num_ports = (device_type >> 4) & 0x000F;
+	if (device_type == MOSCHIP_DEVICE_ID_7843)
+		num_ports = 3;
+	else
+		num_ports = (device_type >> 4) & 0x000F;
 
 	/*
 	 * num_ports is currently never zero as device_type is one of