iommu/amd: Fix variable "iommu" set but not used

The commit dce8d696 ("iommu/amd: Convert to probe/release_device()
call-backs") introduced an unused variable,

drivers/iommu/amd_iommu.c: In function 'amd_iommu_uninit_device':
drivers/iommu/amd_iommu.c:422:20: warning: variable 'iommu' set but not
used [-Wunused-but-set-variable]
  struct amd_iommu *iommu;
                    ^~~~~
Signed-off-by: NQian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/20200509015645.3236-1-cai@lca.pw
Fixes: dce8d696 ("iommu/amd: Convert to probe/release_device() call-backs")
Signed-off-by: NJoerg Roedel <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -397,15 +397,12 @@ static void iommu_ignore_device(struct device *dev)
 static void amd_iommu_uninit_device(struct device *dev)
 {
 	struct iommu_dev_data *dev_data;
-	struct amd_iommu *iommu;
 	int devid;
 
 	devid = get_device_id(dev);
 	if (devid < 0)
 		return;
 
-	iommu = amd_iommu_rlookup_table[devid];
-
 	dev_data = search_dev_data(devid);
 	if (!dev_data)
 		return;