drm/amd/powerplay: remove unused parameter of phm_start_thermal_controller (v2)

Unused.

v2: squash in warning fix (Harry)

Signed-off-by: Evan Quan <evan.quan@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>