drm/i915/lvds: switch to drm_edid_read_switcheroo()

Use drm_edid_read_switcheroo() to switch from struct edid to struct
drm_edid.

Reviewed-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/429cd6f23366cb4cace4fa13cf92ad068aca64dd.1685437501.git.jani.nikula@intel.com