scsi: stex: Fix reboot_notifier leak in probe error path

[ Upstream commit 20da637eb545b04753e20c675cfe97b04c7b600b ]

In stex_probe(), register_reboot_notifier() is called at the beginning,
but if any subsequent initialization step fails, the function returns
without unregistering the notifier, resulting in a resource leak.

Add unregister_reboot_notifier() in the out_disable error path to ensure
proper cleanup on all failure paths.

Fixes: 61b745fa63 ("scsi: stex: Add S6 support")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Link: https://patch.msgid.link/20251104094847.270-1-vulab@iscas.ac.cn
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/scsi/stex.c

@@ -1846,6 +1846,7 @@ out_release_regions:
 out_scsi_host_put:
 	scsi_host_put(host);
 out_disable:
+	unregister_reboot_notifier(&stex_notifier);
 	pci_disable_device(pdev);
 
 	return err;