merge_config.sh: whitespace cleanup

Fix whitespace usage in the clean_up routine.
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Acked-by: John Stultz <john.stultz@linaro.org>
Cc: Michal Marek <mmarek@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>