PCI: remove unnecessary volatile in PCIe hotplug struct controller

Proper memory barriers have been added to order accesses
to ->cmd_busy, so volatile declaration for cmd_busy can
be removed.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/hotplug/pciehp.h

@@ -97,7 +97,7 @@ struct controller {
 	u32 slot_cap;
 	u8 cap_base;
 	struct timer_list poll_timer;
-	volatile int cmd_busy;
+	int cmd_busy;
 	unsigned int no_cmd_complete:1;
 };