RDMA/ucma: Support querying for AF_IB addresses

The sockaddr structure for AF_IB is larger than sockaddr_in6.  The
rdma cm user space ABI uses the latter to exchange address information
between user space and the kernel.

To support querying for larger addresses, define a new query command
that exchanges data using sockaddr_storage, rather than sockaddr_in6.
Unlike the existing query_route command, the new command only returns
address information.  Route (i.e. path record) data is separated.

Signed-off-by: Sean Hefty <sean.hefty@intel.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>