drm/i915/opregion: add support for mailbox #5 EDID

drm/i915/opregion: add support for mailbox #5 EDID

The ACPI OpRegion Mailbox #5 ASLE extension may contain an EDID to be
used for the embedded display. Add support for using it via by adding
the EDID to the list of available modes on the connector, and use it for
eDP when available.

If a panel's EDID is broken, there may be an override EDID set in the
ACPI OpRegion mailbox #5. Use it if available.

Fixes the GPD Win Max display.

Based on original patch series by: Jani Nikula <jani.nikula@intel.com>
https://patchwork.kernel.org/project/intel-gfx/patch/20200828061941.17051-1-jani.nikula@intel.com/

Changes:
 - EDID is copied and validated with drm_edid_is_valid
 - EDID is now only used as a fallback.
 - squashed the two patches

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Co-developed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Anisse Astier <anisse@astier.eu>
Link: https://patchwork.freedesktop.org/patch/msgid/20211229222200.53128-2-anisse@astier.eu