We at least need two times
1. one is in car stage, and the code is in rom, and it is used to
2. one is in linuxbios_ram, and it is in ram, it is used to uncompress payload.
car stage, before call copy_and_run, the stack is already in ram. but
code is still in rom. So at this time we need to balance the lzma
benifit on compress linuxbios_ram and it's own code size increase in
rom. also need to set one extra buffer in ram for every ap code.
Hope we can squash car stage code + linuxbios_ram code into 64k again.