qla4xxx: Do not wait for IO completion, after issuing stop_firmware

Problem:
iSCSI stop_firmware mailbox command is not completing outstanding IO.

Solution:
Do not wait for IO completion after issuing stop_firmware mailbox
command

Signed-off-by: Tej Parkash <tej.parkash@qlogic.com>
Signed-off-by: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: Christoph Hellwig <hch@lst.de>