vfio/pci: add missing identifier name in argument of function prototype

The function prototype is missing an identifier name. Add one.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20210902212631.54260-1-colin.king@canonical.comSigned-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/pci/vfio_pci_core.c

@@ -565,7 +565,7 @@ static bool vfio_pci_dev_below_slot(struct pci_dev *pdev, struct pci_slot *slot)
 }
 
 struct vfio_pci_walk_info {
-	int (*fn)(struct pci_dev *, void *data);
+	int (*fn)(struct pci_dev *pdev, void *data);
 	void *data;
 	struct pci_dev *pdev;
 	bool slot;