drm: xlnx: Fix kerneldoc

Fix a few errors in the kerneldoc. Mostly this addresses missing/renamed
members.

Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240423171859.3953024-3-sean.anderson@linux.dev