iommu/amd: Remove redundant assignment of err

'err' will be initialized and cleanup the redundant initialization.

Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Link: https://lore.kernel.org/r/1621395447-34738-1-git-send-email-zhangshaokun@hisilicon.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/amd/iommu.c

@@ -1785,7 +1785,7 @@ static void __init amd_iommu_init_dma_ops(void)
 
 int __init amd_iommu_init_api(void)
 {
-	int err = 0;
+	int err;
 
 	amd_iommu_init_dma_ops();