Disable display reinitialization on start on RPI by default

This can put PMP/Qt into an endless loop of crashing and restarting on
some systems. The reason is unknown (possibly due to the kind of unclean
way we restore the graphics state on RPI), so disable it to be on the
safe side for now.

resources/settings/settings_description.json

@@ -49,7 +49,7 @@
       },
       {
         "value": "hdmi_poweron",
-        "default": true,
+        "default": false,
         "hidden": true,
         "platforms": [ "oe_rpi" ]
       }