[PATCH] powerpc: Make UP -> SMP kexec work again

For UP to SMP kexec to work we need to jump into pSeries_secondary_smp_init
event on a UP + KEXEC kernel. The secondary cpus will not find their hw_cpu_id
in the paca and so they'll jump into kexec_wait, ready for a kexec.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>