arch/x86/platform/ce4100/ce4100.c: include reboot.h

Fix the build:

  arch/x86/platform/ce4100/ce4100.c: In function 'x86_ce4100_early_setup':
  arch/x86/platform/ce4100/ce4100.c:165:2: error: 'reboot_type' undeclared (first use in this function)

Reported-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>