ARM: stm32: Add optional manufacturing environment to DH STM32MP15xx DHSOM
Add manufacturing environment into STM32MP15xx DH electronics DHSOM
configuration. This environment is part of every board build, but only
takes effect on systems booted with the dh,stm32mp15xx-dhcor-testbench
device tree, i.e. systems populated with factory build of U-Boot.
Signed-off-by: Marek Vasut <marex@denx.de> Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>