video: fbdev: atmel_lcdfb: fix an error code in atmel_lcdfb_probe()

If "sinfo->config" is not found, then return -ENODEV.  Don't
return success.

Fixes: b985172b ("video: atmel_lcdfb: add device tree suport")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Helge Deller <deller@gmx.de>