OMAPDSS: hdmi5: Remove callbacks for the old ASoC DAI driver

Removes the OMAP5 HDMI audio callbacks for the old external DAI driver.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>