Add selinux permissions for ro.usb.uvc.enabled

This CL the selinux rules for the property ro.usb.uvc.enabled which will
be used to toggle UVC Gadget functionality on the Android Device.

Bug: 242344221
Bug: 242344229
Test: Manually tested that the property can only be read at runtime,
      not written to.
Change-Id: I0fd6051666d9554037acc68fa81226503f514a45
diff --git a/private/system_app.te b/private/system_app.te
index 3b92c0f..9116058 100644
--- a/private/system_app.te
+++ b/private/system_app.te
@@ -177,6 +177,9 @@
 # Settings app reads ro.oem_unlock_supported
 get_prop(system_app, oem_unlock_prop)
 
+# Settings app reads ro.usb.uvc.enabled
+get_prop(system_app, usb_uvc_enabled_prop)
+
 # Allow system apps to act as Perfetto producers.
 perfetto_producer(system_app)