QML-UI: fix black squares on some Android devices

It appears that one some Android devices there is an interaction between
Qt and the GL implementation that results in black squares instead of
icons being shown on the screen.

Disabling the GammaAdjust avoids running the shader and fixes this
problem.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-mobile/qml/mobilecomponents/Icon.qml

@@ -38,9 +38,13 @@ Item {
         sourceSize.width: root.width
         sourceSize.height: root.height
     }
+    /*
+     * this appears to cause us to show nothing but black squares instead
+     * of icons on some Android devices
 	    GammaAdjust {
 		anchors.fill: image
 		source: image
 		gamma: root.active ? 3.0 : 1
 	    }
+     */
 }