Enable support for POE on IOSXE (#8853)

We match "iosxe" OS as well for POE polling on cisco devices, as they are using the same MIBs.
This will add support for Catalyst 3850, as well as probably Cat4500 family as well.

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includes/polling/ports/port-poe.inc.php

@@ -25,8 +25,8 @@ if (($device['os'] == 'vrp')) {
         data_update($device, 'poe', $tags, $fields);
         echo 'PoE(vrp) ';
     }
-} elseif (($device['os'] == 'ios')) {
-    // Code for Cisco IOS, tested on 2960X
+} elseif (($device['os'] == 'ios') || ($device['os'] == 'iosxe')) {
+    // Code for Cisco IOS and IOSXE, tested on 2960X
     if (isset($this_port['cpeExtPsePortPwrAllocated'])) {
         // if we have cpeExtPsePortPwrAllocated, we have the complete array so we can populate the RRD
         $upd = "$polled:".$port['cpeExtPsePortPwrAllocated'].':'.$port['cpeExtPsePortPwrAvailable'].':'.