Exclude read-only devices from partitioning backend scan.

src/modules/partition/core/PartitionCoreModule.cpp

@@ -106,7 +106,7 @@ void
 PartitionCoreModule::init()
 {
     CoreBackend* backend = CoreBackendManager::self()->backend();
-    auto devices = backend->scanDevices();
+    auto devices = backend->scanDevices( true );
 
     // Remove the device which contains / from the list
     for ( auto it = devices.begin(); it != devices.end(); )