RDMA/ocrdma: Fixing ocrdma debugfs directory remove

During the ocrdma device remove sequence, the debugfs directory
tree of each ocrdma device needs to be removed. Use
debugfs_remove_recursive instead of debugfs_remove.

Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>