Camera: grant system file perm for Treble

Test: Google Camera app working
Bug: 34786432
Change-Id: Ie14ac8a58a331f96a56fb6fc09318e2d737c4076
diff --git a/public/cameraserver.te b/public/cameraserver.te
index 13c2890..a262940 100644
--- a/public/cameraserver.te
+++ b/public/cameraserver.te
@@ -31,6 +31,9 @@
 allow cameraserver scheduling_policy_service:service_manager find;
 allow cameraserver surfaceflinger_service:service_manager find;
 
+# For HIDL hwservicemanager
+allow cameraserver system_file:dir r_dir_perms;
+
 ###
 ### neverallow rules
 ###