Fix Syslog pattern for system logs

Currently Syslog doesn't log the priority ('<PRI>').

linux/meta/heka.yml

       module_dir: /usr/share/lma_collector/common;/usr/share/heka/lua_modules
       adjust_timezone: true
       config:
-        syslog_pattern: '<%PRI%>%TIMESTAMP% %HOSTNAME% %syslogtag%%msg:::sp-if-no-1st-sp%%msg%\n'
-        fallback_syslog_pattern: '%TIMESTAMP% %HOSTNAME% %syslogtag%%msg:::sp-if-no-1st-sp%%msg%\n'
+        syslog_pattern: '%TIMESTAMP% %HOSTNAME% %syslogtag%%msg:::sp-if-no-1st-sp%%msg%\n'
   input:
     linux_log_stream:
       engine: logstreamer