drm/amd/display: Use drm_display_info for AMD VSDB data

drm/amd/display: Use drm_display_info for AMD VSDB data

Replace the raw EDID byte-walking in parse_amd_vsdb() with a read
from connector->display_info.amd_vsdb, now populated by drm_edid.

Factor out panel type determination into dm_set_panel_type(), which
checks VSDB panel_type, DPCD ext caps, and a luminance heuristic as
fallbacks.

Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Reviewed-by: Mario Limonciello (AMD) <superm1@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>