remove firstboot_prop dontaudit to track the longterm fix

Test: build
Bug: 63801215
Change-Id: I8661833a7dba482a52350d2a9b1215100b43110b
diff --git a/sepolicy/priv_app.te b/sepolicy/priv_app.te
index 63cc3b9..5edad3e 100644
--- a/sepolicy/priv_app.te
+++ b/sepolicy/priv_app.te
@@ -4,4 +4,3 @@
 dontaudit priv_app device:dir read;
 dontaudit priv_app proc_interrupts:file read;
 dontaudit priv_app proc_modules:file read;
-dontaudit priv_app firstboot_prop:file read;