Add DDC support for Trident cards.

Tested on TGUI9440, TGUI9680, 3DImage 9750, Blade3D 9880 and Blade XP.
Signed-off-by: NOndrej Zary <linux@rainbow-software.org>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>