MT#63433 - PBX device page improvements

* Fixes key misnumbering issue on pbx device
buttons

Change-Id: I68efc7995fd0cda5c287fb480f53cb7408237175
(cherry picked from commit 31ffb28a07)

src/components/pages/PbxConfiguration/CscPbxDeviceConfig.vue

@@ -103,12 +103,12 @@ export default {
         },
         keys () {
             const keys = []
-            this.keySets.forEach(($keySet) => {
+            this.keySets.forEach(($keySet, $keySetIndex) => {
                 const $keys = _.get($keySet, 'keys', [])
                 $keys.forEach(($key, $index) => {
                     const key = _.clone($key)
                     key.keySet = $keySet
-                    key.index = $index
+                    key.index = $index + $keySetIndex
                     keys.push(key)
                 })
             })