Fix value returned by 'brightnessGet' DCOP call. The value is now in the range 0-100 (percentage) or -1 if brightness is not supported

Signed-off-by: Michele Calgaro <michele.calgaro@yahoo.it>
(cherry picked from commit 8d7b591826)

src/tdepowersave.cpp

@@ -2938,7 +2938,7 @@ int tdepowersave::brightnessGet() {
 	int retval = -1;
 
 	if (hwinfo->supportBrightness()) {
-		retval = (int)(((float)hwinfo->getCurrentBrightnessLevel() / (float)hwinfo->getMaxBrightnessLevel()-1) * 100.0);
+		retval = (int)(100.0 * hwinfo->getCurrentBrightnessLevel() / hwinfo->getMaxBrightnessLevel());
 	}
 
 	kdDebugFuncOut(trace);