drm/amd/powerplay: remove setting soc floor voltage before sending pptable

SOC voltage is not able to switch and forced to low 0.8V when running HEVC.
Thus the test failed.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Rex Zhu <rezhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>