Evaluate 64 bit for platform_addr_t
All platforms except for legacy Zynq, such as the PCIe based systems or MPSoC, use larger than 32 bit addresses. While we currently get by with smaller addresses this might change in the future and we should consider a move to 64 bit addresses.
I currently don't see any problem just changing the address width. The Zynq platform should continue to work with the required casts and all other platforms currently cast to 64 bit addresses anyway.