Replace make-fit-atf.py with binman. Was: migrate u-boot-rockchip.bin to binman and generate an image for SPI

[Xavier Drudis Ferran]

El Tue, Jul 26, 2022 at 09:08:25PM +0200, Xavier Drudis Ferran deia:
> want u-boot.itb it runs binman -a of-list="rk3399-rock-pi-4b.dts rockchip-itb-u-boot.dts"

Sorry. I mistook the parameter. That would only generate two config entries and 2 fdts in the .itb image. 
We could use some includes, but then we'd need too many .dts files. 
Never mind. 
Maybe we could just stay with make_fit_atf.py