Makes the code more readable by moving variable and usage closer
to each other, which also avoids this build warning in the
!CONFIG_HOTPLUG_CPU case:

  arch/x86/kernel/smpboot.c:105:42: warning: ‘die_complete’ defined but not used [-Wunused-variable]

Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Lan Tianyu <tianyu.lan@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: srostedt@redhat.com
Cc: toshi.kani@hp.com
Cc: imammedo@redhat.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/1409039025-32310-1-git-send-email-tianyu.lan@intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>