fix for vendor_display_prop

Use get_prop(domain..) to allow graphics library to access
vendor_display_prop, so that mediatranscoding type doesn't
need to exposed across the Treble boundary.

bug: 154734285
Change-Id: Id9f45ac8109bc6004f42b5dd66b742033300ab24
diff --git a/vendor/qcom/common/mediatranscoding.te b/vendor/qcom/common/mediatranscoding.te
index 2f9df7f..ab3f09d 100644
--- a/vendor/qcom/common/mediatranscoding.te
+++ b/vendor/qcom/common/mediatranscoding.te
@@ -1,2 +1,2 @@
-dontaudit mediatranscoding vendor_display_prop:file r_file_perms;
+get_prop(domain, vendor_display_prop)