[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>

arch/s390/kernel/smp.c

@@ -685,7 +685,8 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 	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();

arch/s390/kernel/vdso.c

@@ -322,7 +322,8 @@ static int __init vdso_init(void)
 	vdso64_pagelist[vdso64_pages - 1] = virt_to_page(vdso_data);
 	vdso64_pagelist[vdso64_pages] = NULL;
 #ifndef CONFIG_SMP
-	BUG_ON(vdso_alloc_per_cpu(0, S390_lowcore));
+	if (vdso_alloc_per_cpu(0, &S390_lowcore))
+		BUG();
 #endif
 	vdso_init_cr5();
 #endif /* CONFIG_64BIT */