Commit a7be6e5a ("mm: drop useless local parameters of
__register_one_node()") removes the last user of parent_node().

The parent_node() macros in both IP27 and Loongson64 are unnecessary.

Remove it for cleanup.
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/16873/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>