OMAPDSS: add hdmi ops to hdmi_ops and omap_dss_driver

Add two new ops for HDMI: set_infoframe() and set_hdmi_mode(). The first
one can be used to specify the infoframe that should be sent to the HDMI
monitor, and the second one is used to enable HDMI mode (versus DVI
mode).

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>