Reworking of GPU reset logic

[Christian König]

This includes mostly fixes for multi ring lockups and GPU resets, but it should general improve the behavior of the kernel mode driver in case something goes badly wrong.

On the other hand it completely rewrites the IB pool and semaphore handling, so I think there are still a couple of problems in it.

The first four patches were already send to the list, but the current set depends on them so I resend them again.

Cheers,
Christian.