[S390] vdso: fix per cpu area allocation

vdso per cpu area allocation in smp_prepare_cpus() happens with GFP_KERNEL
but irqs disabled. Triggers this one:

Badness at kernel/lockdep.c:2280
Modules linked in:
CPU: 0 Not tainted 2.6.30 #2
Process swapper (pid: 1, task: 000000003fe88000, ksp: 000000003fe87eb8)
Krnl PSW : 0400c00180000000 0000000000083360 (lockdep_trace_alloc+0xec/0xf8)
[...]
Call Trace:
([<00000000000832b6>] lockdep_trace_alloc+0x42/0xf8)
 [<00000000000b1880>] __alloc_pages_internal+0x3e8/0x5c4
 [<00000000000b1b4a>] __get_free_pages+0x3a/0xb0
 [<0000000000026546>] vdso_alloc_per_cpu+0x6a/0x18c
 [<00000000005eff82>] smp_prepare_cpus+0x322/0x594
 [<00000000005e8232>] kernel_init+0x76/0x398
 [<000000000001bb1e>] kernel_thread_starter+0x6/0xc
 [<000000000001bb18>] kernel_thread_starter+0x0/0xc

Fix this by moving the allocation out of the irqs disabled section.
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/smp.c

@@ -687,13 +687,14 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
 #ifndef CONFIG_64BIT
 	if (MACHINE_HAS_IEEE)
 		lowcore->extended_save_area_addr = (u32) save_area;
-#else
-	if (vdso_alloc_per_cpu(smp_processor_id(), lowcore))
-		BUG();
 #endif
 	set_prefix((u32)(unsigned long) lowcore);
 	local_mcck_enable();
 	local_irq_enable();
+#ifdef CONFIG_64BIT
+	if (vdso_alloc_per_cpu(smp_processor_id(), &S390_lowcore))
+		BUG();
+#endif
 	for_each_possible_cpu(cpu)
 		if (cpu != smp_processor_id())
 			smp_create_idle(cpu);