qla2xxx: ISP25xx multiqueue shadow register crash fix.

When creating request/response queues from qla25xx_setup_mode(),
the shadow index register pointers were not being initialized
to point at the registers.

Signed-off-by: Joe Carnuccio <joe.carnuccio@qlogic.com>
Signed-off-by: Saurav Kashyap <saurav.kashyap@qlogic.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>