drm: omapdrm: Use sizeof(*var) instead of sizeof(type) for structures

By linking the sizeof to a variable type the code will be less prone to
bugs due to future type changes of variables.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/gpu/drm/omapdrm/omap_encoder.c b/drivers/gpu/drm/omapdrm/omap_encoder.c
index a20f300..86c977b 100644
--- a/drivers/gpu/drm/omapdrm/omap_encoder.c
+++ b/drivers/gpu/drm/omapdrm/omap_encoder.c
@@ -117,7 +117,7 @@ static int omap_encoder_update(struct drm_encoder *encoder,
 
 		dssdrv->get_timings(dssdev, &t);
 
-		if (memcmp(vm, &t, sizeof(struct videomode)))
+		if (memcmp(vm, &t, sizeof(*vm)))
 			ret = -EINVAL;
 		else
 			ret = 0;