drm/dp: Increase eDP display control capability size

Increase the eDP display control capability size to take into
account the general capability register 703 and 704 that have
recently been added.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Arun R Murthy <arun.r.murthy@intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250206063253.2827017-3-suraj.kandpal@intel.com