dmaengine: idxd: Fix the error handling path in idxd_cdev_register()

If a call to alloc_chrdev_region() fails, the already allocated resources
are leaking.

Add the needed error handling path to fix the leak.

Fixes: 42d279f913 ("dmaengine: idxd: add char driver to expose submission portal to userland")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/1b5033dcc87b5f2a953c413f0306e883e6114542.1650521591.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/idxd/cdev.c

@@ -369,10 +369,16 @@ int idxd_cdev_register(void)
 		rc = alloc_chrdev_region(&ictx[i].devt, 0, MINORMASK,
 					 ictx[i].name);
 		if (rc)
-			return rc;
+			goto err_free_chrdev_region;
 	}
 
 	return 0;
+
+err_free_chrdev_region:
+	for (i--; i >= 0; i--)
+		unregister_chrdev_region(ictx[i].devt, MINORMASK);
+
+	return rc;
 }
 
 void idxd_cdev_remove(void)