drm/amd/display: Enrich the log in MST payload update

[Why & How]
Enrich the log to provide more informatio in MST payload update.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Ariel Bernstein <Eric.Bernstein@amd.com>
Acked-by: Alan Liu <HaoPing.Liu@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>