iommu/amd: remove unused variable flush_addr

Variable flush_addr is being assigned but is never read; it
is redundant and can be removed. Cleans up the clang warning:

drivers/iommu/amd_iommu.c:2388:2: warning: Value stored to 'flush_addr'
is never read
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/iommu/amd_iommu.c

@@ -2382,11 +2382,9 @@ static void __unmap_single(struct dma_ops_domain *dma_dom,
 			   size_t size,
 			   int dir)
 {
-	dma_addr_t flush_addr;
 	dma_addr_t i, start;
 	unsigned int pages;
 
-	flush_addr = dma_addr;
 	pages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
 	dma_addr &= PAGE_MASK;
 	start = dma_addr;