TTM improvement and amdgpu fix

[Christian König]

Hi guys,

TTM has a feature which allows to specify placements for normal operation as well as when all domains are "busy" and don't have free space.

Not very widely used since it was a bit inflexible and required making multiple placement lists. Replace the multiple lists with flags and start to use this in amdgpu as well.

As future improvement we should probably re-work was "busy" means for a domain as well.

Please comment and/or test.

Thanks,
Christian.