drm: Check if the allocation has succeeded before dereferencing newmode

We allocate memory in drm_display_mode_from_vic_index() and use it
without checking the pointer is valid. Fix that.

Signed-off-by: Damien Lespiau <[e-mail]>
Reviewed-by: Alex Deucher <[e-mail]>
Signed-off-by: Daniel Vetter <[e-mail]>

drivers/gpu/drm/drm_edid.c

···
 		return NULL;
 
 	newmode = drm_mode_duplicate(dev, &edid_cea_modes[cea_mode]);
+	if (!newmode)
+		return NULL;
+
 	newmode->vrefresh = 0;
 
 	return newmode;