Don't label simpleperf system_file

The default label for files on /system is already system_file. No
need to explicitly specify it.

Change-Id: If0c92a0da4119a0d8f83b4a3e05101cfcdb9a82d

file_contexts

@@ -160,7 +160,6 @@
 /system/xbin/su		u:object_r:su_exec:s0
 /system/xbin/procrank   u:object_r:procrank_exec:s0
 /system/xbin/perfprofd  u:object_r:perfprofd_exec:s0
-/system/xbin/simpleperf u:object_r:system_file:s0
 /system/vendor/bin/gpsd u:object_r:gpsd_exec:s0
 /system/bin/dnsmasq     u:object_r:dnsmasq_exec:s0
 /system/bin/hostapd     u:object_r:hostapd_exec:s0