drm/amd/powerplay: allow dc request uclk change

when dc set mode or color format in frame buffer
change, it may request clock changes, like dispclk,
dcfclk, uclk. after smu get clock requests, smu
will make decision.

Signed-off-by: hersen wu <hersenxs.wu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>