x86: make Voyager use x86 per-cpu setup.

Impact: standardize all x86 platforms on same setup code

With the preceding changes, Voyager can use the same per-cpu setup
code as all the other x86 platforms.

Signed-off-by: Brian Gerst <brgerst@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>