[ofw] API breakage in trunk

[Sean Hefty]

>It seems we have to stuck with old ib_port_attr_t.
>
>To get new port attribute, we can add these new definition at the end of
>ib_ca_attr_t, I'm assuming its size is OK to expand...

I think it's okay adding it to the end of ib_ca_attr_t.  Some other
alternatives:

1. Define a new structure and interface that provides this data.
2. Define separate ib_port_attr_t for kernel and user space.  Add this to the
kernel, but not user space.  Select a different way for exposing this data to
user space application, if it is needed.