feat(plat/st): add STM32CubeProgrammer support on UART

Add a file to support the STMicroelectronics tool STM32CubeProgrammer
over UART in BL2 for STM32MP15x platform.

This tools is based on protocol defined in AN5275,
"USB DFU/USART protocols used in STM32MP1 Series bootloaders"
based on STM32 MCU protocols (AN3155, "USART protocol used
in the STM32 bootloader").

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Change-Id: I956c95d8de0a94d1eb8e61f043651dae7b838170
2 files changed