drm/amdgpu: fix incorrect judge on sos fw version

for SRIOV the SOS fw of PSP is loaded in hypervisor thus
guest won't tell the version of it, and judging feature by
reading the sos fw version in guest side is completely wrong

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Emily Deng <Emily.Deng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>