ARM: dts: stm32: add SCMI version of STM32 boards (DK1/DK2/ED1/EV1)

Add a "secure" version of STM32 boards based on SCMI when RCC_TZCR.TZEN=1.

Only boards provided by STMicroelectronics are concerned:
-STM32MP157A-DK1
-STM32MP157C-DK2
-STM32MP157C-ED1
-STM32MP157C-EV1

The resources secured by RCC_TZCR.TZEN=1 are managed by OP-TEE
and the associated SCMI services, reset and clock.

These device trees are only supported with stm32mp15_defconfig,
with OP-TEE, SCMI and without SPL support.

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