All the percpu data structure walkers want cpu_possible_map to be
initialized early, but alpha instead populated "hwrpb_cpu_present_mask"
early in setup_smp(), and then initialized cpu_possible_map only much
later.

Thanks go to Heiko Carstens and Dipankar Sarma for noticing.

This fixes it and we can get rid of hwrpb_cpu_present_mask entirely.
Signed-off-by: Linus Torvalds <torvalds@osdl.org>