PCI Hotplug: cpqphp: constify slot_name()

Eliminate this warning:
	warning: return discards qualifiers from pointer target type

Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
diff --git a/drivers/pci/hotplug/cpqphp.h b/drivers/pci/hotplug/cpqphp.h
index 1d5561c..5383600 100644
--- a/drivers/pci/hotplug/cpqphp.h
+++ b/drivers/pci/hotplug/cpqphp.h
@@ -464,7 +464,7 @@
 
 /* inline functions */
 
-static inline char *slot_name(struct slot *slot)
+static inline const char *slot_name(struct slot *slot)
 {
 	return hotplug_slot_name(slot->hotplug_slot);
 }