atmel-ssc: fix misuse of dev_dbg when requested ssc instance is not found

The ssc pointer is not valid when the id is not found in the list.
Convert the message from a debug one into an error message and avoid
dereferencing the bad pointer.

Signed-off-by: Hans-Christian Egtvedt <[e-mail]>
Cc: Kay Sievers <[e-mail]>
Cc: Huang Weiyi <[e-mail]>
Acked-by: Haavard Skinnemoen <[e-mail]>
Cc: David Brownell <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/misc/atmel-ssc.c

···
 
 	if (!ssc_valid) {
 		spin_unlock(&user_lock);
-		dev_dbg(&ssc->pdev->dev, "could not find requested device\n");
+		pr_err("ssc: ssc%d platform device is missing\n", ssc_num);
 		return ERR_PTR(-ENODEV);
 	}