scsi: qla2xxx: Defer processing of GS IOCB calls

This patch defers processing of GS IOCB calls from interrupt context to
avoid hardware spinlock recursion.

Following stack trace is seen

? mod_timer+0x193/0x330
? ql_dbg+0xa7/0xf0 [qla2xxx]
_raw_spin_lock_irqsave+0x31/0x40
qla2x00_start_sp+0x3b/0x250 [qla2xxx]
qla24xx_async_gnl+0x1d3/0x240 [qla2xxx]
qla24xx_fcport_handle_login+0x285/0x290 [qla2xxx]
? vprintk_func+0x20/0x50

Fixes: 726b8548 ("qla2xxx: Add framework for async fabric discovery")
Cc: <stable@vger.kernel.org> # 4.10+
Signed-off-by: Giridhar Malavali <giridhar.malavali@cavium.com>
Signed-off-by: Himanshu Madhani <himanshu.madhani@cavium.com>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>