drivers: video: fbdev: atmel_lcdfb.c: fix error return code

Convert a zero return value on error to a negative one, as returned
elsewhere in the function.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
(
if@p1 (\(ret < 0\|ret != 0\))
{ ... return ret; }
|
ret@p1 = 0
)
... when != ret = e1
when != &ret
*if(...)
{
... when != ret = e2
when forall
return ret;
}

// </smpl>

Signed-off-by: Julia Lawall <[e-mail]>
Acked-by: Nicolas Ferre <[e-mail]>
Signed-off-by: Tomi Valkeinen <[e-mail]>

drivers/video/fbdev/atmel_lcdfb.c

···
 	timings = of_get_display_timings(display_np);
 	if (!timings) {
 		dev_err(dev, "failed to get display timings\n");
+		ret = -EINVAL;
 		goto put_display_node;
 	}
 
 	timings_np = of_find_node_by_name(display_np, "display-timings");
 	if (!timings_np) {
 		dev_err(dev, "failed to find display-timings node\n");
+		ret = -ENODEV;
 		goto put_display_node;
 	}