smp: add missing init.h include

Commit 34db18a054c6 ("smp: move smp setup functions to kernel/smp.c")
causes this build error on s390 because of a missing init.h include:

CC arch/s390/kernel/asm-offsets.s
In file included from /home2/heicarst/linux-2.6/arch/s390/include/asm/spinlock.h:14:0,
from include/linux/spinlock.h:87,
from include/linux/seqlock.h:29,
from include/linux/time.h:8,
from include/linux/timex.h:56,
from include/linux/sched.h:57,
from arch/s390/kernel/asm-offsets.c:10:
include/linux/smp.h:117:20: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'setup_nr_cpu_ids'
include/linux/smp.h:118:20: error: expected '=', ',', ';', 'asm' or '__attribute__' before 'smp_init'

Fix it by adding the include statement.

Signed-off-by: Heiko Carstens <[e-mail]>
Acked-by: WANG Cong <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/smp.h

···
 #include <linux/types.h>
 #include <linux/list.h>
 #include <linux/cpumask.h>
+#include <linux/init.h>
 
 extern void cpu_idle(void);