PCI: pciehp: Reduce PCIe slot_ctrl to 16 bits

4283c70e91dc ("PCI: pciehp: Make pcie_wait_cmd() self-contained") added
a cache of the most recent command written to the Slot Control register.
This register is only 16 bits wide, but the cache ("slot_ctrl") is 32 bits.

Reduce slot_ctrl to a u16 so it matches the register size.  No functional
change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
diff --git a/drivers/pci/hotplug/pciehp.h b/drivers/pci/hotplug/pciehp.h
index 9e5a9fb..b115219 100644
--- a/drivers/pci/hotplug/pciehp.h
+++ b/drivers/pci/hotplug/pciehp.h
@@ -92,7 +92,7 @@
 	struct slot *slot;
 	wait_queue_head_t queue;	/* sleep & wake process */
 	u32 slot_cap;
-	u32 slot_ctrl;
+	u16 slot_ctrl;
 	struct timer_list poll_timer;
 	unsigned long cmd_started;	/* jiffies */
 	unsigned int cmd_busy:1;