ARM: dts: Add STiH407 SoC support

The STiH407 is advanced multi-HD AVC processor with 3D graphics acceleration
and 1.5-GHz ARM Cortex-A9 SMP CPU.

Acked-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>