drm/amd/display: Add min clock init for DML21 mode programming

drm/amd/display: Add min clock init for DML21 mode programming

[WHY & HOW]
0 stream cases do not go through any DML validation which leaves DCN
clocks in unoptimized states.

If requesting DML validation or programming with 0 streams, program
DCN clocks to lowest DPM state.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Ovidiu Bunea <ovidiu.bunea@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>