drm/display/dp_mst: convert to struct drm_edid

Convert the topology manager to use struct drm_edid, add
drm_dp_mst_edid_read() that returns drm_edid, and rewrite the old
drm_dp_mst_get_edid() to use it.

Note that the old drm_get_edid() ended up calling
drm_connector_update_edid_property(). This responsibility is now
deferred to drivers, which all do it anyway after calling
drm_dp_mst_edid_read() or drm_dp_mst_get_edid().

Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/9c32e5c241934093fc4144eed4c01155e1f03af1.1685437501.git.jani.nikula@intel.com