qla2xxx: Disable laser for ISP2031 while unloading driver.

Nameserver data on FC switch is not refreshed when
qla2xxx driver is unloaded. Disabling laser for
ISP2031 will force FC switch to rescan ports and
clear fdmi entries from Nameserver.

Signed-off-by: Himanshu Madhani <himanshu.madhani@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>