drm/amd/pm: move bootup values retrieving to ->sw_init

Firsrt of all, the operations involved is to interact with
VBIOS. They are fully supported at ->sw_init phase.

Secondly, the new mechanism to upload pptable to SMU is
introduced. With the new mechanism, the pptable transferring
has to be via PSP. That requires the pptable ucode(and necessary
bootupp values retrieving) must be ready before ->hw_init phase of PSP.

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