stm32mp1: update device tree files ...

The drivers are also updated to reflect the changes.
Set RCC as non-secure.

Change-Id: I568fa1f418355830ad1d4d1cdcdb910fb362231b
Signed-off-by: Yann Gautier <yann.gautier@st.com>

stm32mp1: Add device tree files ...

Those device tree files are taken from STM32MP1 U-Boot and Linux.
And they are updated to fit TF-A needs.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>