feat(stm32mp1): updates for STM32MP13 device tree compilation

Add stm32mp13_bl2.dtsi files.
Update compilation variables for STM32MP13.

Change-Id: Ia3aa3abfe09c04c1a57541e565c212aa094e285c
Signed-off-by: Yann Gautier <yann.gautier@st.com>
2 files changed