[media] ivtvfb: 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. Also use the
aligned fix.line_length and not the (possible) unaligned xres_virtual.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Ian Armstrong <ian@iarmst.demon.co.uk>
Signed-off-by: Andy Walls <awalls@md.metrocast.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/ivtv/ivtvfb.c

@@ -836,7 +836,8 @@ static int ivtvfb_pan_display(struct fb_var_screeninfo *var, struct fb_info *inf
 	u32 osd_pan_index;
 	struct ivtv *itv = (struct ivtv *) info->par;
 
-	osd_pan_index = (var->xoffset + (var->yoffset * var->xres_virtual))*var->bits_per_pixel/8;
+	osd_pan_index = var->yoffset * info->fix.line_length
+		      + var->xoffset * info->var.bits_per_pixel / 8;
 	write_reg(osd_pan_index, 0x02A0C);
 
 	/* Pass this info back the yuv handler */