Allow llkd to stat() /proc/sysrq-trigger

06-26 20:01:16.860   971   971 I auditd  : type=1400 audit(0.0:8): avc: denied { getattr } for comm="llkd" path="/proc/sysrq-trigger" dev="proc" ino=4026532062 scontext=u:r:llkd:s0 tcontext=u:object_r:proc_sysrq:s0 tclass=file permissive=0

Bug: 192305350
Test: Build for aosp_arm64-eng
Change-Id: Ia6342ebc974f469e0e5d5e2f527d870c8a686b87
diff --git a/private/llkd.te b/private/llkd.te
index f218dec..9c96dfb 100644
--- a/private/llkd.te
+++ b/private/llkd.te
@@ -41,7 +41,7 @@
 
 # live lock watchdog process allowed to dump process trace and
 # reboot because orderly shutdown may not be possible.
-allow llkd proc_sysrq:file w_file_perms;
+allow llkd proc_sysrq:file rw_file_perms;
 allow llkd kmsg_device:chr_file w_file_perms;
 
 ### neverallow rules