scsi: qla2xxx: Fix a NULL pointer dereference

BUG: KASAN: null-ptr-deref in qla24xx_handle_plogi_done_event+0x134/0x9f0 [qla2xxx]
Read of size 4 at addr 00000000000000a0 by task swapper/2/0

CPU: 2 PID: 0 Comm: swapper/2 Not tainted 5.2.0-dbg+ #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
Call Trace:
 <IRQ>
 dump_stack+0x8a/0xd6
 __kasan_report.cold+0x5/0x41
 kasan_report+0x16/0x20
 __asan_load4+0x7e/0x80
 qla24xx_handle_plogi_done_event+0x134/0x9f0 [qla2xxx]
 qla2x00_els_dcmd2_sp_done+0x15f/0x230 [qla2xxx]
 qla24xx_els_ct_entry+0x3b3/0x610 [qla2xxx]
 qla24xx_process_response_queue+0x514/0x10e0 [qla2xxx]
 qla24xx_msix_rsp_q+0x80/0x100 [qla2xxx]
 __handle_irq_event_percpu+0x72/0x450
 handle_irq_event_percpu+0x74/0xf0
 handle_irq_event+0x5e/0x8f
 handle_edge_irq+0x13a/0x320
 handle_irq+0x30/0x40
 do_IRQ+0x91/0x190
 common_interrupt+0xf/0xf
 </IRQ>
RIP: 0010:default_idle+0x31/0x230

Fixes: 8777e431 ("scsi: qla2xxx: Migrate NVME N2N handling into state machine") # v4.19.
Cc: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Tested-by: Himanshu Madhani <hmadhani@marvell.com>
Reviewed-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/qla2xxx/qla_iocb.c

@@ -2755,7 +2755,8 @@ static void qla2x00_els_dcmd2_sp_done(srb_t *sp, int res)
 		} else {
 			memset(&ea, 0, sizeof(ea));
 			ea.fcport = fcport;
-			ea.rc = res;
+			ea.data[0] = MBS_COMMAND_COMPLETE;
+			ea.sp = sp;
 			qla24xx_handle_plogi_done_event(vha, &ea);
 		}