Add support for building u-boot for ODROID C2. The steps used to build the FIP is not only different compared to other boards like gxl and g12a boards, but it also differs ever so slightly compared to other gxbb boards, so some work still needs to be done to support *other* gxbb boards in u-boot-amlogic. Signed-off-by: Ferass El Hafidi <funderscore@postmarketos.org> Part-of: <https://gitlab.postmarketos.org/postmarketOS/pmaports/-/merge_requests/7569>