drm/amd/display: Add register key and status for edid

[Why]
Register key for AE or QA do regression test.  New edid status for
check.

[How]
Add register key edid_read_retry_times.
Add new edid status EDID_FALL_BACK.

Signed-off-by: Jing Zhou <Jing.Zhou@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Eryk Brol <eryk.brol@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>