Allow init to access user mode helpers

This is in host sepolicy, looked like we pruned it because we didn't
need it - but now we do.

Bug: 297019386
Test: Run VM with encrypted storage, no denials
Change-Id: I6cd5f6bf98e9089ef7c3945c29242daea527592f

microdroid/system/private/init.te

@@ -57,6 +57,9 @@ allow init tmpfs:lnk_file { getattr read relabelfrom };
 # setrlimit
 allow init self:global_capability_class_set sys_resource;
 
+# Set usermodehelpers.
+allow init { usermodehelper sysfs_usermodehelper }:file rw_file_perms;
+
 # Remove /dev/.booting and load /debug_ramdisk/* files
 allow init tmpfs:file { getattr unlink };