[RESEND][PATCH 1/2][POWERPC] PIKA Warp: Update platform code to supportRev B boards

[Paul Mackerras]

It doesn't help that both of these patches have the same subject line,
nor that it starts with "Re:". :(

Also, I find the statement "A change to the dts to get gpios correct
broke the led code" a bit opaque.  It doesn't tell me in what way it
was broken or what this patch does to correct, or even what the change
was in enough detail that I could find the change in the git
repository.

Paul.