IB/qib: Remove destroy queue pair code

Destroy QP functionality in rdmavt will be used instead.
Remove the remove_qp function being called exclusively by destroy qp code.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>