powerpc/4xx: Fix warning in kilauea.dtb

Currently I see:
  DTC     arch/powerpc/boot/kilauea.dtb
Warning (reg_format): "reg" property in /plb/ppc4xx-msi@C10000000 has invalid length (12 bytes) (#address-cells == 1, #size-cells == 1)

It appears that unlike the other platforms handled by 3fb79338
"powerpc/4xx: Adding PCIe MSI support" this platform does not use address-cells=2.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Josh Boyer <jwboyer@gmail.com>
Cc: Rupjyoti Sarmah <rsarmah@apm.com>
Cc: Tirumala R Marri <tmarri@apm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: devicetree@vger.kernel.org (open list:OPEN FIRMWARE AND...)
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>