V4L/DVB (11168): pvrusb2: Define value for a null sub-device ID

Signed-off-by: NMike Isely <isely@pobox.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/pvrusb2/pvrusb2-devattr.h

@@ -33,6 +33,7 @@
 */
 
 
+#define PVR2_CLIENT_ID_NULL 0
 #define PVR2_CLIENT_ID_MSP3400 1
 #define PVR2_CLIENT_ID_CX25840 2
 #define PVR2_CLIENT_ID_SAA7115 3