NTB: ntb_transport: fix debugfs_remove_recursive

The call to debugfs_remove_recursive(qp->debugfs_dir) of the sub-level
directory must not be later than
debugfs_remove_recursive(nt_debugfs_dir) of the top-level directory.
Otherwise, the sub-level directory will not exist, and it would be
invalid (panic) to attempt to remove it.  This removes the top-level
directory last, after sub-level directories have been cleaned up.

Signed-off-by: Allen Hubbe <Allen.Hubbe@dell.com>
Fixes: e26a5843

 ("NTB: Split ntb_hw_intel and ntb_transport drivers")
Signed-off-by: Jon Mason <jdmason@kudzu.us>