ARM: dts: rockchip: add to support emac for rk3036 SoCs

This patch adds the emac device node for rk3036 SoCs.
We need to let mac clock under the DPLL which is able to provide
the accurate 50MHz what mac_ref need, since that will cause some
unstable things if the cpufreq is working.

Signed-off-by: Xing Zheng <zhengxing@rock-chips.com>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
Cc: linux-rockchip@lists.infradead.org
Cc: Xing Zheng <zhengxing@rock-chips.com>
Cc: Heiko Stuebner <heiko@sntech.de>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>