Allow lmkd read memcg stats.

Currently lmkd is not able to read memcg info. The mem/swap usage
info are used by lmkd to ugrade medium pressure events to critical
level.

Test: tested on gobo
Bug: 65180281
Change-Id: I19d0eb53d5e754c176ffeda1b5d07049e6af8570

public/lmkd.te

@@ -27,6 +27,9 @@ allow lmkd appdomain:process sigkill;
 # Clean up old cgroups
 allow lmkd cgroup:dir { remove_name rmdir };
 
+# Allow to read memcg stats
+allow lmkd cgroup:file r_file_perms;
+
 # Set self to SCHED_FIFO
 allow lmkd self:capability sys_nice;