rpmb: fix error path in rpmb_dev_register()

Until this patch was rpmb_dev_register() always freeing rdev in the error
path. However, past device_register() it must not do that since the memory
is now managed by the device even if it failed to register properly. So fix
this by doing a put_device() before returning the error code.

Fixes the smatch warning:
drivers/misc/rpmb-core.c:204 rpmb_dev_register()
warn: freeing device managed memory (leak): 'rdev'

Fixes: 1e9046e3a154 ("rpmb: add Replay Protected Memory Block (RPMB) subsystem")
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Jens Wiklander <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Ulf Hansson <[e-mail]>

drivers/misc/rpmb-core.c

···
 	rdev->dev.parent = dev;
 
 	ret = device_register(&rdev->dev);
-	if (ret)
-		goto err_id_remove;
+	if (ret) {
+		put_device(&rdev->dev);
+		return ERR_PTR(ret);
+	}
 
 	dev_dbg(&rdev->dev, "registered device\n");
 
 	return rdev;
 
-err_id_remove:
-	mutex_lock(&rpmb_mutex);
-	ida_simple_remove(&rpmb_ida, rdev->id);
-	mutex_unlock(&rpmb_mutex);
 err_free_dev_id:
 	kfree(rdev->descr.dev_id);
 err_free_rdev: