powerpc: Re-order the call to smp_setup_cpu_maps()

It makes more sense to do it before intializing xmon() as xmon might
use the info in there. We do want to register the console early
though in case we want some functioning printk's in the cpu map setup.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>