Minimize microdroid public policy

Like core sepolicy.

Bug: 232023812
Test: atest MicrodroidHostTests MicrodroidTests
Change-Id: I704f8da4656d3bacf327792a2445d15aba8ecf2a
diff --git a/microdroid/system/private/init.te b/microdroid/system/private/init.te
index c83bcdb..4441d12 100644
--- a/microdroid/system/private/init.te
+++ b/microdroid/system/private/init.te
@@ -440,3 +440,7 @@
 r_dir_file(init, vendor_kernel_modules)
 allow init self:capability sys_module;
 allow init vendor_kernel_modules:system module_load;
+
+allow init tmpfs:chr_file relabelfrom;
+allow init kmsg_device:chr_file { getattr write relabelto };
+allow init kmsg_debug_device:chr_file { open write relabelto };