x86/PCI: only check for spinlock being held in SMP kernels

spin_is_locked() is always false on UP kernels: spin_lock_irqsave() does no
locking, so we can't tell whether the lock is held or not.  Therefore,
this warning is only valid for SMP kernels.

CC: Myron Stowe <myron.stowe@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

arch/x86/pci/i386.c

@@ -57,7 +57,7 @@ static struct pcibios_fwaddrmap *pcibios_fwaddrmap_lookup(struct pci_dev *dev)
 {
 	struct pcibios_fwaddrmap *map;
 
-	WARN_ON(!spin_is_locked(&pcibios_fwaddrmap_lock));
+	WARN_ON_SMP(!spin_is_locked(&pcibios_fwaddrmap_lock));
 
 	list_for_each_entry(map, &pcibios_fwaddrmappings, list)
 		if (map->dev == dev)