x86/voyager: fix boot breakage caused by x86: boot secondary cpus through initial_code

Impact: boot up secondary CPUs as well on x86/Voyager systems

This commit:

| commit 3e970473
| Author: Glauber Costa <gcosta@redhat.com>
| Date:   Wed May 28 13:01:54 2008 -0300
|
|     x86: boot secondary cpus through initial_code

removed the use of initialize_secondary.  However, it didn't update
voyager, so the secondary cpus no longer boot.  Fix this by adding the
initial_code switch to voyager as well.

Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>