drm/amd/display: Remove config update

[Why]
Prevent overwrite of dc->config.use_default_clock_table, as it should be
pre-configured.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Taimur Hassan <syed.hassan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>