drm/tidss: Fix missing includes and struct decls

drm/tidss: Fix missing includes and struct decls

Fix missing includes and struct declarations. Even if these don't cause
any compile issues at the moment, it's good to have them correct.

Reviewed-by: Aradhya Bhatia <aradhya.bhatia@linux.dev>
Tested-by: Parth Pancholi <parth.pancholi@toradex.com>
Tested-by: Jayesh Choudhary <j-choudhary@ti.com>
Reviewed-by: Devarsh Thakkar <devarsht@ti.com>
Link: https://lore.kernel.org/r/20250723-cdns-dsi-impro-v5-2-e61cc06074c2@ideasonboard.com
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>