ramips: mt7621: bringup dsa master on preinit

DSA requires master netdev to be up before any of its slave ports.
Bring it up during preinit so that the first lan port can be used
on failsafe.

Signed-off-by: Chuanhong Guo <gch981213@gmail.com>

target/linux/ramips/mt7621/base-files/lib/preinit/07_mt7621_bringup_dsa_master

@@ -0,0 +1,22 @@
+#!/bin/sh
+
+. /lib/functions.sh
+
+mt7621_bringup_dsa_master() {
+    local board=$(board_name)
+    local masterif
+
+    case "$board" in
+    ubiquiti,edgerouterx|\
+	ubiquiti,edgerouterx-sfp)
+        masterif="dsa"
+        ;;
+    *)
+        masterif="eth0"
+        ;;
+    esac
+
+    ifconfig $masterif up
+}
+
+boot_hook_add preinit_main mt7621_bringup_dsa_master