ephemeral_app: restore /dev/ashmem open permissions

ephemeral_app domain doesn't distinguish between apps that target Q vs
ones target pre-Q. Restore ashmem permissions for older apps.

Bug: 130054503
Test: start com.nextlatam.augmentedfaces instant app
Change-Id: I490323cce96d69e561fc808426a9dfba2aeac30f
diff --git a/private/app_neverallows.te b/private/app_neverallows.te
index 17f4111..fcdd653 100644
--- a/private/app_neverallows.te
+++ b/private/app_neverallows.te
@@ -339,6 +339,7 @@
 # They must use ASharedMemory NDK API instead.
 neverallow {
   all_untrusted_apps
+  -ephemeral_app
   -untrusted_app_25
   -untrusted_app_27
 } ashmem_device:chr_file open;
diff --git a/private/ephemeral_app.te b/private/ephemeral_app.te
index a94c637..1283e21 100644
--- a/private/ephemeral_app.te
+++ b/private/ephemeral_app.te
@@ -65,7 +65,7 @@
 allow ephemeral_app system_server:udp_socket {
         connect getattr read recvfrom sendto write getopt setopt };
 
-allow ephemeral_app ashmem_device:chr_file { getattr read ioctl lock map append write };
+allow ephemeral_app ashmem_device:chr_file rw_file_perms;
 
 ###
 ### neverallow rules