omapdrm: hdmi.h: extend hdmi_core_data with CEC fields

Extend the hdmi_core_data struct with the additional fields needed
for CEC.

Also fix a simple typo in a comment.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>