x86: Fix sparse non-ANSI function warnings in smpboot.c

Fix sparse warning for non-ANSI function declaration:

  arch/x86/kernel/smpboot.c:100:30: warning: non-ANSI function declaration of function 'cpu_hotplug_driver_lock'
  arch/x86/kernel/smpboot.c:105:32: warning: non-ANSI function declaration of function 'cpu_hotplug_driver_unlock'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <20110108195914.95d366ea.randy.dunlap@oracle.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>