drm/amdgpu/soc15: always load the psp module

Regardless of whether the user has selected psp fw loading or
not.  It's still needed for GPU reset among other things.
There are already guards in place to avoid setting up the full
psp if PSP fw loading is not enabled.

Reviewed-by: Rex Zhu <rezhu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>