[PATCH -next] iommu/intel: silence a variable set but not used

[Qian Cai <cai@lca.pw>]

The commit "iommu/vt-d: Probe DMA-capable ACPI name space devices"
introduced a compilation warning due to the "iommu" variable in
for_each_active_iommu() but never used the for each element, i.e,
"drhd->iommu".

drivers/iommu/intel-iommu.c: In function 'probe_acpi_namespace_devices':
drivers/iommu/intel-iommu.c:4639:22: warning: variable 'iommu' set but
not used [-Wunused-but-set-variable]
  struct intel_iommu *iommu;

Silence the warning the same way as in the commit d3ed71e5cc50
("drivers/iommu/intel-iommu.c: fix variable 'iommu' set but not used")

Signed-off-by: Qian Cai <cai@lca.pw>
---
 drivers/iommu/intel-iommu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index b431cc6f6ba4..2897354a341a 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4636,7 +4636,8 @@ static int __init platform_optin_force_iommu(void)
 static int __init probe_acpi_namespace_devices(void)
 {
 	struct dmar_drhd_unit *drhd;
-	struct intel_iommu *iommu;
+	/* To avoid a -Wunused-but-set-variable warning. */
+	struct intel_iommu *iommu __maybe_unused;
 	struct device *dev;
 	int i, ret = 0;
 
-- 
1.8.3.1