usb: cdc-acm: send ZLP for Telit 3G Intel based modems

BugLink: https://bugs.launchpad.net/bugs/1818237

commit 34aabf91 upstream.

Telit 3G Intel based modems require zero packet to be sent if
out data size is equal to the endpoint max packet size.
Signed-off-by: Daniele Palmas <dnlplm@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/usb/class/cdc-acm.c

@@ -1885,6 +1885,13 @@ static const struct usb_device_id acm_ids[] = {
 	.driver_info = IGNORE_DEVICE,
 	},
 
+	{ USB_DEVICE(0x1bc7, 0x0021), /* Telit 3G ACM only composition */
+	.driver_info = SEND_ZERO_PACKET,
+	},
+	{ USB_DEVICE(0x1bc7, 0x0023), /* Telit 3G ACM + ECM composition */
+	.driver_info = SEND_ZERO_PACKET,
+	},
+
 	/* Exclude Exar USB serial ports */
 	{ USB_DEVICE(0x04e2, 0x1400), .driver_info = IGNORE_DEVICE, },
 	{ USB_DEVICE(0x04e2, 0x1401), .driver_info = IGNORE_DEVICE, },