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: NTej Parkash <tej.parkash@qlogic.com>
Signed-off-by: NVikas Chaudhary <vikas.chaudhary@qlogic.com>
Reviewed-by: NMike Christie <michaelc@cs.wisc.edu>
Signed-off-by: NChristoph Hellwig <hch@lst.de>