RDMA/device: Consolidate ib_device per_port data into one place

There is no reason to have three allocations of per-port data. Combine
them together and make the lifetime for all the per-port data match the
struct ib_device.

Following patches will require more port-specific data, now there is a
good place to put it.

Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>