V4L/DVB (12402): em28xx: fix: some em2710 chips use a different vendor ID

Thanks to hermann pitton <hermann-pitton@arcor.de> for pointing this new
variation.
Tested-by: hermann pitton <hermann-pitton@arcor.de>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/video4linux/CARDLIST.em28xx

   0 -> Unknown EM2800 video grabber             (em2800)        [eb1a:2800]
-  1 -> Unknown EM2750/28xx video grabber        (em2820/em2840) [eb1a:2820,eb1a:2821,eb1a:2860,eb1a:2861,eb1a:2870,eb1a:2881,eb1a:2883]
+  1 -> Unknown EM2750/28xx video grabber        (em2820/em2840) [eb1a:2710,eb1a:2820,eb1a:2821,eb1a:2860,eb1a:2861,eb1a:2870,eb1a:2881,eb1a:2883]
   2 -> Terratec Cinergy 250 USB                 (em2820/em2840) [0ccd:0036]
   3 -> Pinnacle PCTV USB 2                      (em2820/em2840) [2304:0208]
   4 -> Hauppauge WinTV USB 2                    (em2820/em2840) [2040:4200,2040:4201]

drivers/media/video/em28xx/em28xx-cards.c

@@ -1549,6 +1549,8 @@ struct usb_device_id em28xx_id_table[] = {
 			.driver_info = EM2750_BOARD_UNKNOWN },
 	{ USB_DEVICE(0xeb1a, 0x2800),
 			.driver_info = EM2800_BOARD_UNKNOWN },
+	{ USB_DEVICE(0xeb1a, 0x2710),
+			.driver_info = EM2820_BOARD_UNKNOWN },
 	{ USB_DEVICE(0xeb1a, 0x2820),
 			.driver_info = EM2820_BOARD_UNKNOWN },
 	{ USB_DEVICE(0xeb1a, 0x2821),