ARM: dts: msm: Add phy related properties for ethernet on msm8996

Add mdio_bus_id and phy_addr to access phy device
instead of scanning mdio bus. It will reduce time
cost during ethernet driver loading.

Change-Id: Ifb1574d4a68944a087dcafb12bc79098bc3156e4
Signed-off-by: Zou Shunxiang <shunxian@codeaurora.org>