MIPS: Octeon: add missing of_node_put()

MIPS: Octeon: add missing of_node_put()

The call to of_find_node_by_name returns a node pointer with refcount
incremented thus it must be explicitly decremented here after the last
usage.

Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Patchwork: https://patchwork.linux-mips.org/patch/19558/
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org