ARM: STi: DT: Enable second sdhci controller for stih416 b2020 boards.

The second controller is only present on the stih416 SoC. Also
mark this as non-removeable as its eMMC.

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Acked-by: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@st.com>