ARM: STi: Update platform level menuconfig 'help'

Encompass newer STiH4{07,10} and STiH418 SoC based platforms.

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