luci-app-irqbalance: upgrade uci-defaults for ucitrack handling to use json

Conversion of the 'uci-defaults' script for ucitrack handling to the new
json processing.

Signed-off-by: Florian Eckert <fe@dev.tdt.de>

applications/luci-app-irqbalance/root/etc/uci-defaults/90_luci-irqbalance

@@ -1,10 +0,0 @@
-#!/bin/sh
-
-uci -q batch <<-EOF >/dev/null
-    delete ucitrack.@irqbalance[-1]
-    add ucitrack irqbalance
-    set ucitrack.@irqbalance[-1].init=irqbalance
-    commit ucitrack
-EOF
-
-exit 0

applications/luci-app-irqbalance/root/usr/share/ucitrack/luci-app-irqbalance.json

@@ -0,0 +1,4 @@
+{
+	"config": "irqbalance",
+	"init": "irqbalance"
+}