Don't try to convert negative mW to dBm in AP power report

Netdisco/Changes

@@ -21,6 +21,7 @@
 
   * Set of Port Name (description) fixed to assume OK dialog response
   * Default class of a PoE port is 0 if not otherwise defined
+  * Don't try to convert negative mW to dBm in AP power report
 
 2.019003 - 2013-10-27
 

Netdisco/lib/App/Netdisco/Web/Plugin/Report/ApRadioChannelPower.pm

@@ -22,7 +22,7 @@ sub port_tree {
     foreach my $device (@$devices) {
         my $power2;
 
-        if ( defined( $device->power ) && $device->power ) {
+        if ( defined( $device->power ) && $device->power > 0 ) {
             $power2 = sprintf( "%.1f",
                 10.0 * CORE::log( $device->power ) / CORE::log(10) );
         }