staging: panel: fix checkpatch warnings

Now checkpatch clean.

$ find drivers/staging/panel -name "*.[ch]"|xargs ./scripts/checkpatch.pl \
-f --terse --nosummary|cut -f3- -d":"|sort |uniq -c|sort -n

2  WARNING: Single statement macros should not use a do {} while (0) loop

Signed-off-by: Toshiaki Yamane <yamanetoshi@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>