Enable extra CPUs that may be supported by virt board, including
R4x00 (R4000 in QEMU), Cavium Octeon (Octeon68XX in QEMU), loongson2e,
loongson2f.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>