arch/x86/kernel/apm_32.c: remove duplicated #include

Removed duplicated include file <linux/smp_lock.h> in
arch/x86/kernel/apm_32.c.

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>