[PATCH] ipw2200: Add pci .shutdown handler

If we don't disable the card in the pci .shutdown method, there might be
pending interrupts still in the interrupt line after a reboot on some
platform. This patch fixes the problem by disable the hardware in the pci
.shutdown method.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>