drm/amd/pm: Use the PPTable from VBIOS for beige_goby

Switch from softPPTable to VBIOS PPTable.

v2: drop extra parens (Alex)

Signed-off-by: Chengming Gui <Jack.Gui@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>