ARM: dts: stm32: Update ck_flexgen_08 frequency.

Spurious characters are displayed on U-Boot console.
Usart2 clock is ck_flexgen_08 and its frequency is set
to an incorrect value.

Update ck_flexgen_08 frequency from 100MHz to 64MHz.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
1 file changed