[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/vdso.c b/arch/s390/kernel/vdso.c
index 25a6a82..690e178 100644
--- a/arch/s390/kernel/vdso.c
+++ b/arch/s390/kernel/vdso.c
@@ -322,7 +322,8 @@
 	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 */