The MIPS_CPU_* definitions have now filled the first 32-bits, and are
getting longer since they're written in hex without zero padding. Adding
my 8 extra MIPS_CPU_* definitions which I haven't upstreamed yet this is
getting increasingly ugly as the comments get shifted progressively to
the right. Its also error prone, and I've seen this cause mistakes on 3
separate occasions now, not helped by it being a conflict hotspot.
Convert all the MIPS_CPU_* definitions to the form (1ull << x). Humans
are better at incrementing than shifting.