tools/bootconfig: Fix tracing_on option checking in ftrace2bconf.sh

Since tracing_on indicates only "1" (default) or "0", ftrace2bconf.sh
only need to check the value is "0".

Link: https://lkml.kernel.org/r/163077087144.222577.6888011847727968737.stgit@devnote2

Fixes: 55ed4560 ("tools/bootconfig: Add tracing_on support to helper scripts")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

tools/bootconfig/scripts/ftrace2bconf.sh

@@ -239,8 +239,8 @@ instance_options() { # [instance-name]
 		emit_kv $PREFIX.cpumask = $val
 	fi
 	val=`cat $INSTANCE/tracing_on`
-	if [ `echo $val | sed -e s/f//g`x != x ]; then
-		emit_kv $PREFIX.tracing_on = $val
+	if [ "$val" = "0" ]; then
+		emit_kv $PREFIX.tracing_on = 0
 	fi
 
 	val=`cat $INSTANCE/current_tracer`