ARM: dts: iwg23s-sbc: Add HDMI support

This patch adds HDMI video output support to the iwg23s board
from iWave. Due to a problem with the bootloader not dealing
with the configuration of one of the pins correctly, we have
to use a gpio-hog for the interrupt line to make sure the pin
is configured as GPIO-input when requesting the interrupt.

Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>