drm/amd/powerplay: move maximum sustainable clock retrieving to .hw_init

Since DAL settings come between .hw_init and .late_init of SMU. And
DAL needs to know the maximum sustainable clocks.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reported-and-Tested-by: Flora Cui <flora.cui@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>