staging: fbtft: fbtft_device: Fix checkpatch warning

Fix checkpatch.pl warning:
Block comments use * on subsequent lines
Block comments use a trailing */ on a separate line

Signed-off-by: Anson Jacob <ansonjacob.aj@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>