drm/edid: start propagating drm_edid to lower levels

We'll need to propagate drm_edid everywhere. This is a clunky start, but
a start nonetheless. We'll eventually convert all of the EDID parsing to
struct drm_edid.

Initially, we'll just create the struct drm_edid in stack. This will be
the compat layer for legacy struct edid code. In the future, we'll have
EDID read return drm_edid objects.

v2: Add legacy init helper.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/000452fddedbaf7f473ac25d4dde2502e60b8e39.1652097712.git.jani.nikula@intel.com