ARM: dts: stm32: Fix timer initialization for stm32 MCU's board

Commit 4b2be78a ("time: Fix get_ticks being non-monotonic")
puts in evidence that get_ticks is called before timer initialization.
Fix it by initializing timer before relocation.

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