feat(stm32mp1): introduce new flag for STM32MP13

STM32MP13 is a variant of STM32MP1, with a single Cortex-A7, and no
Cortex-M4.
There is only one DDR port.
SP_min is not supported, only OP-TEE can be used as monitor.
STM32MP13 uses the header v2.0 format for stm32image generation
for BL2.

Change-Id: Ie5b0e3230c5e064fe96f3561fc5b3208914dea53
Signed-off-by: Yann Gautier <yann.gautier@st.com>
3 files changed