dmaengine: bcm-sba-raid: fix device leak on probe

Make sure to drop the reference taken when looking up the mailbox device
during probe on probe failures and on driver unbind.

Fixes: 743e1c8 ("dmaengine: Add Broadcom SBA RAID driver")
Cc: stable@vger.kernel.org	# 4.13
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://patch.msgid.link/20251117161258.10679-4-johan@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

Author: jhovold

drivers/dma/bcm-sba-raid.c

@@ -1699,7 +1699,7 @@ static int sba_probe(struct platform_device *pdev)
 	/* Prealloc channel resource */
 	ret = sba_prealloc_channel_resources(sba);
 	if (ret)
-		goto fail_free_mchan;
+		goto fail_put_mbox;
 
 	/* Check availability of debugfs */
 	if (!debugfs_initialized())
@@ -1729,6 +1729,8 @@ static int sba_probe(struct platform_device *pdev)
 fail_free_resources:
 	debugfs_remove_recursive(sba->root);
 	sba_freeup_channel_resources(sba);
+fail_put_mbox:
+	put_device(sba->mbox_dev);
 fail_free_mchan:
 	mbox_free_channel(sba->mchan);
 	return ret;
@@ -1744,6 +1746,8 @@ static void sba_remove(struct platform_device *pdev)
 
 	sba_freeup_channel_resources(sba);
 
+	put_device(sba->mbox_dev);
+
 	mbox_free_channel(sba->mchan);
 }