drm/amdgpu: Don't resume IOMMU after incomplete init

Check kfd->init_complete in kgd2kfd_iommu_resume, consistent with other
kgd2kfd calls. This should fix IOMMU errors on resume from suspend when
KFD IOMMU initialization failed.

Reported-by: Matt Fagnani <matt.fagnani@bell.net>
Link: https://lore.kernel.org/r/4a3b225c-2ffd-e758-4de1-447375e34cad@bell.net/
Link: https://bugzilla.kernel.org/show_bug.cgi?id=217170
Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2454
Cc: Vasant Hegde <vasant.hegde@amd.com>
Cc: Linux regression tracking (Thorsten Leemhuis) <regressions@leemhuis.info>
Cc: stable@vger.kernel.org
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Tested-by: Matt Fagnani <matt.fagnani@bell.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>