stm32mp1: introduce STM32MP1 discovery boards

Add the device tree files to support the 2 discovery boards: DK1 & DK2.

Change-Id: I90b4797dc69bd0aab1b643a72c932ead48a03c1f
Signed-off-by: Yann Gautier <yann.gautier@st.com>
4 files changed