Revert "powerpc: implement the DMA_ATTR_NO_WARN attribute"

BugLink: https://bugs.launchpad.net/bugs/1644596

This reverts commit 96530c8a.

The backports that fix bug #1633128 for xenial, in particular the backport
of upstream commit a9a62c93 ("dma-mapping: introduce the
DMA_ATTR_NO_WARN attribute"), introduce a regression.
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

arch/powerpc/kernel/iommu.c

@@ -479,8 +479,7 @@ int ppc_iommu_map_sg(struct device *dev, struct iommu_table *tbl,
 
 		/* Handle failure */
 		if (unlikely(entry == DMA_ERROR_CODE)) {
-			if (!(dma_get_attr(DMA_ATTR_NO_WARN, attrs)) &&
-			    printk_ratelimit())
+			if (printk_ratelimit())
 				dev_info(dev, "iommu_alloc failed, tbl %p "
 					 "vaddr %lx npages %lu\n", tbl, vaddr,
 					 npages);
@@ -777,8 +776,7 @@ dma_addr_t iommu_map_page(struct device *dev, struct iommu_table *tbl,
 					 mask >> tbl->it_page_shift, align,
 					 attrs);
 		if (dma_handle == DMA_ERROR_CODE) {
-			if (!(dma_get_attr(DMA_ATTR_NO_WARN, attrs)) &&
-			    printk_ratelimit())  {
+			if (printk_ratelimit())  {
 				dev_info(dev, "iommu_alloc failed, tbl %p "
 					 "vaddr %p npages %d\n", tbl, vaddr,
 					 npages);