- Remove second license, the first was not that different and should be
fine.
- Add nexus_attach(), and do not perform its task in nexus_probe() any
more.
- Remove nexus_write_ivar(), since it was quite pointless.
- Remove superfluous devinfo members.
- Clean up some comments, minor style issues and prototypes.
struct ofw_nexus_reg. Implement UPA device memory management in the
nexus driver.
Adapt the psycho driver to these changes, and do some minor cleanup work
while being there.