ARM: dts: Hook up internal PHY on Arndale

While the Linux driver stack is capable of figuring this out for itself
document the fact that we really do use the internal PHY even with the
directly wired hub on the board to save anyone else having to work this
out for themselves.

Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>