[S390] vdso: compile fix

!CONFIG_SMP:

arch/s390/kernel/vdso.c: In function 'vdso_init':
arch/s390/kernel/vdso.c:325: error: incompatible type for argument 2 of 'vdso_alloc_per_cpu'

Also move the code out of the BUG_ON statement since it won't be
executed on !CONFIG_BUG. And that would be a bug.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 9c0ccb5..2d337cb 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -685,7 +685,8 @@
 	if (MACHINE_HAS_IEEE)
 		lowcore->extended_save_area_addr = (u32) save_area;
 #else
-	BUG_ON(vdso_alloc_per_cpu(smp_processor_id(), lowcore));
+	if (vdso_alloc_per_cpu(smp_processor_id(), lowcore))
+		BUG();
 #endif
 	set_prefix((u32)(unsigned long) lowcore);
 	local_mcck_enable();