drm/amdgpu: switch to common rlc_autoload helper

drop IP specific psp function for rlc autoload since
the autoload_supported was introduced to mark ASICs
that support rlc_autoload

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Reviewed-by: Guchun Chen <guchun.chen@amd.com>
Reviewed-by: John Clements <john.clements@amd.com>
Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>