ARM: dts: sun7i: Add BCM53125 switch nodes to the lamobo-r1 board

Now that we have a proper binding for Ethernet switches hanging off
different buses, and a driver for the BCM53125 switch, add its Device
Tree as a child MDIO node, at MDIO address 30 (Broadcom pseudo-PHY
address) and describe the ports layout of the Lamobo R1 board.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>