zd1211rw: Fix alignment problems

Shaddy Baddah found an alignment problem with zd1211rw driver at
2007-11-19. This patch fixes it, it is based on the patch proposed by
Herbert Xu. The alignment 4 has been the agreed value on the
linux-wireless mailing list.

Notify that the problem does only affect the old zd1211rw softmac
driver and not the zd1211rw-mac80211 driver. Daniel Drake has
already provided a patch for the replacement of the softmac
driver, which this patch will break.

Signed-off-by: Ulrich Kunitz <kune@deine-taler.de>
Signed-off-by: John W. Linville <linville@tuxdriver.com>