ARM: dts: sun7i: Add CAN node

The A20 SoC has an on-board CAN controller.
This patch adds the device node.

The CAN controller is inherited from the A10 SoC and uses the same driver.

This patch is adapted from the description in
Documentation/devicetree/bindings/net/can/sun4i_can.txt

Signed-off-by: Patrick Menschel <menschel.p@posteo.de>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>