linux-phytec-fsl

ARM: dts: rockchip: enable gmac on rk3288-firefly

This was left out of the original firefly board definition due to the
ethernet support going completely through the network tree, making the
underlying nodes unavailable.

Now that everything is present enable the gmac on the firefly.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>