ARM: dts: sk-rzg1e: add Ether pins

Add the (previously omitted) Ether/PHY pin data to the SK-RZG1E board's
device tree.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>