feat(stm32mp1): get CPU info from SYSCFG on STM32MP13

The IDC register from DBGMCU is duplicated in SYSCFG. As SYSCFG is
always accessible, get chip ID and revision ID from there on STM32MP13.

Change-Id: Ib0b6e8f68a2934a45ec0012f69db6c12a60adb17
Signed-off-by: Yann Gautier <yann.gautier@st.com>
3 files changed