drm/amdgpu/psp: ignore psp response status

In some cases, psp response status is not 0 even there is no
problem while the command is submitted. Some version of PSP FW
doesn't write 0 to that field.
So here we would like to only print a warning instead of an error
during psp initialization to avoid breaking hw_init and it doesn't
return -EINVAL.

Signed-off-by: Aaron Liu <aaron.liu@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Reviewed-by: Xiangliang <Yu&lt;Xiangliang.Yu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Feifei Xu <Feifei.Xu@amd.com>
Reviewed-by: Paul Menzel <pmenzel+amd-gfx@molgen.mpg.de>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>