[partition] In logging, distinguish more cases

- While winnowing devices, the zram and nullptr cases
   were mixed together; split them, for the sake of
   logging more accurately.
 - While here, fix up some coding-style issues.

src/modules/partition/core/DeviceList.cpp

@@ -113,28 +113,32 @@ QList< Device* > getDevices( DeviceType which, qint64 minimumSize )
 
     // Remove the device which contains / from the list
     for ( DeviceList::iterator it = devices.begin(); it != devices.end(); )
-        if ( ! ( *it ) ||
-                ( *it )->deviceNode().startsWith( "/dev/zram" )
+        if ( !( *it ) )
+        {
+            cDebug() << "  .. Skipping nullptr device";
+            it = erase( devices, it);
+        }
+        else if ( ( *it )->deviceNode().startsWith( "/dev/zram" )
         )
         {
             cDebug() << "  .. Removing zram" << it;
-            it = erase(devices, it );
+            it = erase( devices, it );
 
         }
         else if ( writableOnly && hasRootPartition( *it ) )
         {
             cDebug() << "  .. Removing device with root filesystem (/) on it" << it;
-            it = erase(devices, it );
+            it = erase( devices, it );
         }
         else if ( writableOnly && isIso9660( *it ) )
         {
             cDebug() << "  .. Removing device with iso9660 filesystem (probably a CD) on it" << it;
-            it = erase(devices, it );
+            it = erase( devices, it );
         }
         else if ( (minimumSize >= 0) && !( (*it)->capacity() > minimumSize ) )
         {
             cDebug() << "  .. Removing too-small" << it;
-            it = erase(devices, it );
+            it = erase( devices, it );
         }
         else
             ++it;