USB: serial: omninet: add device id for Zyxel Omni 56K Plus

Add device id for Zyxel Omni 56K Plus modem, this modem include:

USB chip:
NetChip
NET2888

Main chip:
901041A
F721501APGF

Another modem using the same chips is the Zyxel Omni 56K DUO/NEO,
could be added with the right USB ID.
Signed-off-by: Alexandre GRIVEAUX <agriveaux@deutnet.info>
Cc: stable@vger.kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>

drivers/usb/serial/omninet.c

@@ -26,6 +26,7 @@
 
 #define ZYXEL_VENDOR_ID		0x0586
 #define ZYXEL_OMNINET_ID	0x1000
+#define ZYXEL_OMNI_56K_PLUS_ID	0x1500
 /* This one seems to be a re-branded ZyXEL device */
 #define BT_IGNITIONPRO_ID	0x2000
 
@@ -40,6 +41,7 @@ static void omninet_port_remove(struct usb_serial_port *port);
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(ZYXEL_VENDOR_ID, ZYXEL_OMNINET_ID) },
+	{ USB_DEVICE(ZYXEL_VENDOR_ID, ZYXEL_OMNI_56K_PLUS_ID) },
 	{ USB_DEVICE(ZYXEL_VENDOR_ID, BT_IGNITIONPRO_ID) },
 	{ }						/* Terminating entry */
 };