plugins/screencast: fix damage region position

Damage reported from the output is output-local and therefore doesn't
need to be translated.

I tested this with Chromium, where the damage region on my 3-monitor
setup was always -4k something on the right screen, -2k on the middle
one and correct on the left screen. With this change I can confirm that
the position is now correctly reported for the right screen.

src/plugins/screencast/outputscreencastsource.cpp

@@ -86,7 +86,7 @@ uint OutputScreenCastSource::refreshRate() const
 void OutputScreenCastSource::report(const QRegion &damage)
 {
     if (!damage.isEmpty()) {
-        Q_EMIT frame(scaleRegion(damage.translated(-m_output->geometry().topLeft()), m_output->scale()));
+        Q_EMIT frame(scaleRegion(damage, m_output->scale()));
     }
 }
 
@@ -97,7 +97,7 @@ void OutputScreenCastSource::resume()
     }
 
     connect(m_output, &Output::outputChange, this, &OutputScreenCastSource::report);
-    report(m_output->geometry());
+    report(m_output->rect());
 
     m_active = true;
 }