tiny-printf: endless loop for %llu format

Hi,

I am trying to boot AM335x platform via TFTP and found another one issue related to tiny-printf:

print_size() in lib/display_options.c relies on

printf("%llu Bytes%s", size, s);

and it surprisingly leads to infinite looping when tiny-printf is used in SPL. So, I am afraid that TFTP in SPL is currently broken for every board.