drm/amdgpu: disable the IP module if early_init returns -ENOENT (v2)

If we run into a part with a harvest configuration where the entire
IP block is unusable, just disable the IP block.

v2: fix logic as noted by Christian

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