using "echo foobar > filename" does not work, use tee instead

I guess the execute_command appends another redirection to stdout when
calling the command. Therefore the first redirect is useless.

lib/setup-storage/Commands.pm

@@ -515,7 +515,7 @@ sub build_raid_commands {
       # do not remove ; from echo line. Otherwise it will not work
       if ($FAI::do_init_tasks) { # no sync when initial installation
 	&FAI::push_command(
-          "echo frozen > /sys/block/md$id/md/sync_action",
+          "echo frozen | tee /sys/block/md$id/md/sync_action",
           "exist_/dev/md$id", "nosync_md$id" );
       }