x86: setup_per_cpu_areas() cleanup

Impact: cleanup

__alloc_bootmem and __alloc_bootmem_node do panic
for us in case of fail so no need for additional
checks here.

Also lets use pr_*() macros for printing.

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>