[PATCH] x86-64: use safe_apic_wait_icr_idle in smpboot.c - x86_64

The functionality provided by the new safe_apic_wait_icr_idle is being
open-coded all over "kernel/smpboot.c". Use safe_apic_wait_icr_idle
instead to consolidate code and ease maintenance.

Signed-off-by: Fernando Luis Vazquez Cao <fernando@oss.ntt.co.jp>
Signed-off-by: Andi Kleen <ak@suse.de>