drm/amd/display: Assign socclk in dml

Assign socclk_khz value from dcn4x.

Reviewed-by: Ariel Bernstein <eric.bernstein@amd.com>
Signed-off-by: Sridevi Arvindekar <sarvinde@amd.com>
Signed-off-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>