ARM: DT: STiH407: Add systrace pin configuration

This patch adds the pin config for systrace for
STiH407 family silicon.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@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>