PCI/ATS: Add inline to pci_prg_resp_pasid_required()

commit fff42928ade591969836ff49888d063b829ac888 upstream.

Fix unused function warning when compiled with CONFIG_PCI_PASID
disabled.

Fixes: e5567f5f6762 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>