feat(st-ddr): add STM32MP2 driver

Add driver to support DDR on STM32MP2 platform. It drives the DDR PHY
and its firmware, as well as the DDR controller.

Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Signed-off-by: Maxime Méré <maxime.mere@foss.st.com>
Change-Id: I93de2db1b9378d5654e76b3bf6f3407d80bc4ca5
41 files changed