Clear out the user response struct correctly.

Fixes: 29c8d9eb ("IB: Add vmw_pvrdma driver")
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAdit Ranadive <aditr@vmware.com>
Signed-off-by: NDoug Ledford <dledford@redhat.com>