STAGING: rtl8192u: fix checkpatch error by adding space after switch

This patch fixes the following checkpatch error:
ERROR: space required before the open parenthesis '('

Signed-off-by: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>