rdmavt has a down call to client drivers to retrieve a crafted card
name.

This name should be the IB defined name.

Rather than craft the name each time it is needed, simply retrieve
the IB allocated name from the IB device.

Update the function name to reflect its application.

Clean up driver code to match this change.
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>