DC doesn't seem to have a fallback path either.

So when interrupts doesn't work any more we are pretty much busted no
matter what.
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NChunming Zhou <david1.zhou@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>