cxgb3 - bug fixes

Hi Jeff,

I'm submitting a set of bug fixes for inclusion in 2.6.21. The patches are built against Linus'git tree.

Here is a brief description:
- Avoid deadlock when the interface is brought down
- Rework the MAC hang workaround since it was failing if the peer interface was brought down
- add missing RNIC register setting and CPL handler

Cheers,
Divy