drm/omap: HDMI5: Fix FC HSW value

For some reason the HDMI FC's HSW value is programmed to hsw-1. There's
no indication in the documentation that this would be correct, and no
other blanking value needs -1 either.

So remove the -1.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>