drm/amdgpu:fix vpost_needed routine

1,cleanup description/comments
2,for FIJI & passthrough, force post when smc fw version below 22.15
3,for other cases, follow regular rules

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
1 file changed