Widgets, iOS: don't tell the input panel to hide on focus out

On iOS, autoSIP is handled by the platform plugin. We therefore
avoid letting widgets tell the input panel to hide on focus out
so we can gain better control over this from the plugin.

Note that we could also set QApplicationPrivate::autoSipEnabled
to false and achieve the same. But since autoSIP is logically set
on iOS, it's better to report it as set in case the app asks.

Change-Id: I96c68bc446a1e299fd57afe03a9e273491df08a7
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>