Deprecate maverick-raspberrylite?

[fnoop]

maverick-raspberrylite is for the older single core cpu based boards, like the rpi 1 and rpi zero. Now that the zero 2 has been released with arm7l multi cores, we should probably just drop full support for the older arm6 single cpu boards. The main maverick-raspberry build will boot and mostly work with the older boards, just not the arm7l optimized components like opencv and tensorflow, which are largely useless on the older boards anyway.