Only do the aspect fallback test once, after screen dimensions are final.

src/conio/vidmodes.c

@@ -375,10 +375,6 @@ int load_vmode(struct video_stats *vs, int mode)
 	vs->currattr = vparams[i].default_attr;
 	vs->aspect_width = vparams[i].aspect_width;
 	vs->aspect_height = vparams[i].aspect_height;
-	if (vs->aspect_width == 0 || vs->aspect_height == 0 || ciolib_r2yptr == NULL || ciolib_y2rptr == NULL) {
-		vs->aspect_width = vs->scrnwidth;
-		vs->aspect_height = vs->scrnheight;
-	}
 	if (vparams[i].xres > 0)
 		vs->scrnwidth = vparams[i].xres;
 	else