microdroid: Add rules for /sys/kernel/mm/pgsize_migration/enabled

The dynamic linker needs to read this node to determine how it should
load ELF files. See page_size_migration_supported() [1]

Allow the node to be enabled/disabled by init.

[1] https://cs.android.com/android/platform/superproject/main/+/3d5e32517bbf56e9c69e3133a1b849b97cd6aa1d:bionic/linker/linker_phdr.cpp;l=709-721

Bug: 342520142
Bug: 330117029
Bug: 327600007
Bug: 330767927
Bug: 328266487
Bug: 329803029
Test: no avc deined in logcat
Change-Id: I91381e36943ea0387ff245e924ddab53a4928a05
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
diff --git a/microdroid/system/private/init.te b/microdroid/system/private/init.te
index 4441d12..67af209 100644
--- a/microdroid/system/private/init.te
+++ b/microdroid/system/private/init.te
@@ -303,6 +303,7 @@
   sysfs_power
   sysfs_fs_f2fs
   sysfs_dm
+  sysfs_pgsize_migration
 }:file w_file_perms;
 
 allow init {