IB/IPoIB: ibX: failed to create mcg debug file

When udev renames the netdev devices, ipoib debugfs entries does not
get renamed. As a result, if subsequent probe of ipoib device reuse the
name then creating a debugfs entry for the new device would fail.

Also, moved ipoib_create_debug_files and ipoib_delete_debug_files as part
of ipoib event handling in order to avoid any race condition between these.

Fixes: 1732b0ef ([IPoIB] add path record information in debugfs)
Cc: stable@vger.kernel.org # 2.6.15+
Signed-off-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: Shamir Rabinovitch <shamir.rabinovitch@oracle.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>