unify extended vlan id swconfig attributes. AR8216 and PSB6970 used "pvid", IP17xx used "tag" and RTL8306 called it "vid". Change all to "vid" and annotate the description with the valid ID range.

SVN-Revision: 23419

target/linux/generic/files/drivers/net/phy/rtl8306.c

@@ -829,7 +829,7 @@ static struct switch_attr rtl_vlan[] = {
 	{
 		RTL_VLAN_REGATTR(VID),
 		.name = "vid",
-		.description = "VLAN ID",
+		.description = "VLAN ID (1-4095)",
 		.max = 4095,
 	},
 };