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 <hans-christian.egtvedt@atmel.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Huang Weiyi <weiyi.huang@gmail.com>
Acked-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/misc/atmel-ssc.c

@@ -35,7 +35,7 @@ struct ssc_device *ssc_request(unsigned int ssc_num)
 
 	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);
 	}