ARM: dts: STiH418: Add B2199 board support

B2199 HDK is the reference board for STiH418 SoC.
It has the following characteristics:
 - 3GB DDR3
 - 8GB eMMC / SD-Card slot
 - 32MB NOR Flash
 - 1 x Gbit Ethernet
 - 1 x USB3.0 port
 - 2 x USB2.0 ports
 - 1 x Sata or Mini-PCIe port
 - 1 x WiFi 802.11ac (Quantenna)
 - 1 x HDMI out
 - 1 x HDMI in
 - 1 x SPDIF

Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>