vt8623fb: use display information in info not in var for panning

We must not use any information in the passed var besides xoffset,
yoffset and vmode as otherwise applications might abuse it.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/video/vt8623fb.c

@@ -620,13 +620,14 @@ static int vt8623fb_pan_display(struct fb_var_screeninfo *var, struct fb_info *i
 	unsigned int offset;
 
 	/* Calculate the offset */
-	if (var->bits_per_pixel == 0) {
-		offset = (var->yoffset / 16) * var->xres_virtual + var->xoffset;
+	if (info->var.bits_per_pixel == 0) {
+		offset = (var->yoffset / 16) * info->var.xres_virtual
+		       + var->xoffset;
 		offset = offset >> 3;
 	} else {
 		offset = (var->yoffset * info->fix.line_length) +
-			 (var->xoffset * var->bits_per_pixel / 8);
-		offset = offset >> ((var->bits_per_pixel == 4) ? 2 : 1);
+			 (var->xoffset * info->var.bits_per_pixel / 8);
+		offset = offset >> ((info->var.bits_per_pixel == 4) ? 2 : 1);
 	}
 
 	/* Set the offset */