ARM: configs: stm32: Enable MMC_ARMMMCI and EXT3_FS support

-Enable MMC_ARMMCI support to add SDIO support for
STM32F4 and STM32F7 SoCs family

-Enable EXT3_FS support to be able to read rootfs from MMC partition
formatted in EXT2/3/4

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>