PCI/ATS: Add inline to pci_prg_resp_pasid_required()

Fix unused function warning when compiled with CONFIG_PCI_PASID
disabled.

Fixes: e5567f5f67 ("PCI/ATS: Add pci_prg_resp_pasid_required() interface.")
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

include/linux/pci-ats.h

@@ -67,7 +67,7 @@ static inline int pci_max_pasids(struct pci_dev *pdev)
 	return -EINVAL;
 }
 
-static int pci_prg_resp_pasid_required(struct pci_dev *pdev)
+static inline int pci_prg_resp_pasid_required(struct pci_dev *pdev)
 {
 	return 0;
 }