refactor(st): move board info in common code

Create a function stm32_display_board_info() that will display ST
board information, from a parameter taken from OTP fuse. The code
is just moved from STM32MP1 part to common directory.

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I9e12fe98b5aabc7791cf2c9d48a38fbf2b219f9e