ARM: dts: nanopi-neo-air: Add WiFi / eMMC

Enable the WiFi (AP6212) chip and eMMC support for the NanoPi NEO Air.

This patch was originally submitted by Jelle van der Waa. Martin Kelly
modified it to compile on the latest kernel, fixed up some review
comments from Maxime Ripard, and re-tested the patch.

Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Cc: linux-sunxi@googlegroups.com
Cc: devicetree@vger.kernel.org
Signed-off-by: Jelle van der Waa <jelle@vdwaa.nl>
Signed-off-by: Martin Kelly <mkelly@xevo.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>