sepolicy: grant thermal-engine sys_boot

thermal-engine needs the sys_boot capability in order to power off
the phone in cases where emergency thermal mitigation is necessary.

bug 32950327

Change-Id: Ia6703c28e4bd655e9f14f4a9f6df01c1c819a7be
(cherry picked from commit 4e17673432496827d1bc991cff2cf77b6fc08a24)
diff --git a/sepolicy/thermal-engine.te b/sepolicy/thermal-engine.te
index 6315b5b..7946afc 100644
--- a/sepolicy/thermal-engine.te
+++ b/sepolicy/thermal-engine.te
@@ -25,3 +25,4 @@
   allow thermal-engine diag_device:chr_file rw_file_perms;
 ')
 
+allow thermal-engine self:capability sys_boot;