RDMA/cm: Fix memory leak in cm_add/remove_one

In the process of moving the debug counters sysfs entries, the commit
mentioned below eliminated the cm_infiniband sysfs directory.

This sysfs directory was tied to the cm_port object allocated in procedure
cm_add_one().

Before the commit below, this cm_port object was freed via a call to
kobject_put(port->kobj) in procedure cm_remove_port_fs().

Since port no longer uses its kobj, kobject_put(port->kobj) was eliminated.
This, however, meant that kfree was never called for the cm_port buffers.

Fix this by adding explicit kfree(port) calls to functions cm_add_one()
and cm_remove_one().

Note: the kfree call in the first chunk below (in the cm_add_one error
flow) fixes an old, undetected memory leak.

Fixes: c87e65cf

 ("RDMA/cm: Move debug counters to be under relevant IB device")
Link: https://lore.kernel.org/r/20190916071154.20383-2-leon@kernel.org
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>