drm/radeon: remove radeon_connector_edid() and stop using edid_blob_ptr

drm/radeon: remove radeon_connector_edid() and stop using edid_blob_ptr

radeon_connector_edid() copies the EDID from edid_blob_ptr as a side
effect if radeon_connector->edid isn't initialized. However, everywhere
that the returned EDID is used, the EDID should have been set
beforehands.

Only the drm EDID code should look at the EDID property, anyway, so stop
using it.

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Pan
Cc: amd-gfx@lists.freedesktop.org
Reviewed-by: Robert Foss <rfoss@kernel.org>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b2bdec9161ddcbf79c8516aeea508a9903bd0074.1715353572.git.jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula@intel.com>