[PATCH -next] iommu/arm-smmu-v3: Fix build error without CONFIG_PCI_ATS

[YueHaibing]

If CONFIG_PCI_ATS is not set, building fails:

drivers/iommu/arm-smmu-v3.c: In function arm_smmu_ats_supported:
drivers/iommu/arm-smmu-v3.c:2325:35: error: struct pci_dev has no member named ats_cap; did you mean msi_cap?
  return !pdev->untrusted && pdev->ats_cap;
                                   ^~~~~~~

ats_cap should only used when CONFIG_PCI_ATS is defined,
so use #ifdef block to guard this.

Fixes: bfff88ec1afe ("iommu/arm-smmu-v3: Rework enabling/disabling of ATS for PCI masters")
Signed-off-by: YueHaibing <yuehaibing@xxxxxxxxxx>
---
 drivers/iommu/arm-smmu-v3.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 66bf641..44ac9ac 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2313,7 +2313,7 @@ static void arm_smmu_install_ste_for_dev(struct arm_smmu_master *master)
 
 static bool arm_smmu_ats_supported(struct arm_smmu_master *master)
 {
-	struct pci_dev *pdev;
+	struct pci_dev *pdev __maybe_unused;
 	struct arm_smmu_device *smmu = master->smmu;
 	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
 
@@ -2321,8 +2321,10 @@ static bool arm_smmu_ats_supported(struct arm_smmu_master *master)
 	    !(fwspec->flags & IOMMU_FWSPEC_PCI_RC_ATS) || pci_ats_disabled())
 		return false;
 
+#ifdef CONFIG_PCI_ATS
 	pdev = to_pci_dev(master->dev);
 	return !pdev->untrusted && pdev->ats_cap;
+#endif
 }
 
 static void arm_smmu_enable_ats(struct arm_smmu_master *master)
-- 
2.7.4