RDMA/core: Add common iWARP query port

RDMA/core: Add common iWARP query port

Add support for a common iWARP query port function, the new function
includes a common code that is used by the iWARP devices to update the
port attributes like max_mtu, active_mtu, state, and phys_state, the
function also includes a call for the driver-specific query_port callback
to query the device-specific port attributes.

Signed-off-by: Kamal Heib <kamalheib1@gmail.com>
Link: https://lore.kernel.org/r/20190807103138.17219-4-kamalheib1@gmail.com
Signed-off-by: Doug Ledford <dledford@redhat.com>