ARM: DT: STiH407: Add NAND flash controller pin configuration

This patch adds NAND flash support controller pin configuration
for STiH407 family silicon.

Signed-off-by: Christophe Kerello <christophe.kerello@st.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>