drm/amdgpu: remove duplicated kfd_resume_iommu

Remove duplicated kfd_resume_iommu which already runs
in mdgpu_amdkfd_device_init.

Tested-By: Ken Moffat <zarniwhoop@ntlworld.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>