ARM: STi: DT: Add STiH407 family tsin2 pinctrl configuration

tsin2 channel can be configured for either serial or parallel data
transfer. This patch adds the pinctrl config for both possibilities.

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