ARM: dts: STiH407: Move non-removable property to board file

Due to 96board which uses mmc0 node for SD card, the non-removable
property must be moved from STiH407-family to board file for B2120
and B2199 boards.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>