ramips: fix MT7621 gsw handling

based on https://forum.openwrt.org/viewtopic.php?pid=323671#p323671

Signed-off-by: John Crispin <john@phrozen.org>

target/linux/ramips/patches-4.4/0519-gsw_mt7621.patch

@@ -0,0 +1,31 @@
+--- a/drivers/net/ethernet/mediatek/mt7530.c
++++ b/drivers/net/ethernet/mediatek/mt7530.c
+@@ -539,6 +539,7 @@
+ 		u8 etags = priv->vlan_entries[i].etags;
+ 		u32 val;
+ 
++#ifndef CONFIG_SOC_MT7621
+ 		/* vid of vlan */
+ 		val = mt7530_r32(priv, REG_ESW_VLAN_VTIM(i));
+ 		if (i % 2 == 0) {
+@@ -549,7 +550,7 @@
+ 			val |= (vid << 12);
+ 		}
+ 		mt7530_w32(priv, REG_ESW_VLAN_VTIM(i), val);
+-
++#endif
+ 		/* vlan port membership */
+ 		if (member)
+ 			mt7530_w32(priv, REG_ESW_VLAN_VAWD1, REG_ESW_VLAN_VAWD1_IVL_MAC |
+@@ -569,7 +570,11 @@
+ 		mt7530_w32(priv, REG_ESW_VLAN_VAWD2, val);
+ 
+ 		/* write to vlan table */
++#ifdef CONFIG_SOC_MT7621
++		mt7530_vtcr(priv, 1, vid);
++#else
+ 		mt7530_vtcr(priv, 1, i);
++#endif
+ 	}
+ 
+ 	/* Port Default PVID */