drm/amd/display: fix pixel rate update sequence

The k1/k2 pixel rate dividers in dccg should only be updated on stream enable
and do not actually depend on whether odm combine is active.

This removes an on flip update of these and fixes the calculate function
to ignore odm status for dp steams.

Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Dmytro Laktyushkin <dmytro.laktyushkin@amd.com>
Reviewed-by: Ariel Bernstein <Eric.Bernstein@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>