init: Make encryption action an argument to mkdir

FscryptSetDirectoryPolicy no longer tries to infer the action from the
filename. Well mostly; it still assumes top-level directories in /data
should be encrypted unless the mkdir arguments say otherwise, but
it warns.

Bug: 26641735
Test: boot, check log messages
Change-Id: Id6d2cea7fb856f17323897d85cf6190c981b443c
Signed-off-by: Omkar Chandorkar <gotenksIN@aospa.co>

prebuilts/init/init.aospa-hub.rc

@@ -1,4 +1,4 @@
 on post-fs-data
     # Create an additional OTA package directory that unlike
     # /data/ota_package will not be touched by GmsCore.
-    mkdir /data/hub_updates 0770 system cache
+    mkdir /data/hub_updates 0770 system cache encryption=Require