/vendor/priv-app is added to the permitted paths for the default ns

We will have apps under /vendor/priv-app. Add the path to the permitted
paths so that the apks and so libs under the directory can be loaded.

Bug: 35301609
Test: None since we don't have priv vendor app yet.
Change-Id: Ida998adb2e180852b1922e9933f25b988517399e