RDMA/restrack: don't use uaccess_kernel()

uaccess_kernel() isn't sufficient to determine if an rdma resource is
user-mode or not.  For example, resources allocated in the add_one()
function of an ib_client get falsely labeled as user mode, when they
are kernel mode allocations.  EG: mad qps.

The result is that these qps are skipped over during a nldev query
because of an erroneous namespace mismatch.

So now we determine if the resource is user-mode by looking at the object
struct's uobject or similar pointer to know if it was allocated for user
mode applications.

Fixes: 02d8883f

 ("RDMA/restrack: Add general infrastructure to track RDMA resources")
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>