staging: rtl8192u: fix alignment in r819xU_cmdpkt.h

This patch fixes alignment issues in r819xU_cmdpkt.h to improve code
readability.

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