drm/amd/powerplay: add function get current clock freq interface for navi10

add function of get_current_clk_freq_by_table for navi10.

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>