drm/amd/display: skip program clock when allow seamless boot

[Why]
Driver program dpp clock calculate by pipe split config but hw config is single pipe.

[How]
Skip programming clock when allow seamless boot.
After porgramming pipe config, seamless boot flag will be clear.

Signed-off-by: Lewis Huang <Lewis.Huang@amd.com>
Reviewed-by: Eric Yang <eric.yang2@amd.com>
Acked-by: Wayne Lin <waynelin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>