drm/amd/powerplay: add sclk sysfs interface support for navi10

miss sclk support in force_clk_levels function

Signed-off-by: Kevin Wang <kevin1.Wang@amd.com>
Reviewed-by: Xiaojie Yuan <xiaojie.yuan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>