rpi_temp: remove unused variables (causing shellcheck failure)

plugins/raspberry-pi/rpi_temp

@@ -1,11 +1,6 @@
 #! /bin/sh
 # (c) 2013 - LGPL - Steve Schnepp <steve.schnepp@pwkf.org>
 
-pluginfull="$0"                 # full name of plugin
-plugin="${0##*/}"               # name of plugin
-pidfile="$MUNIN_PLUGSTATE/munin.$plugin.pid"
-cache="$MUNIN_PLUGSTATE/munin.$plugin.value"
-
 
 if [ ! -r "/sys/class/thermal/thermal_zone0/temp" ]
 then