dma-mapping: Remove dma_check_mask()

sme_active() is an x86-specific function so it's better not to call it from
generic code. Christoph Hellwig mentioned that "There is no reason why we
should have a special debug printk just for one specific reason why there
is a requirement for a large DMA mask.", so just remove dma_check_mask().

Signed-off-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190806044919.10622-4-bauerman@linux.ibm.com

kernel/dma/mapping.c

@@ -291,12 +291,6 @@ void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
 }
 EXPORT_SYMBOL(dma_free_attrs);
 
-static inline void dma_check_mask(struct device *dev, u64 mask)
-{
-	if (sme_active() && (mask < (((u64)sme_get_me_mask() << 1) - 1)))
-		dev_warn(dev, "SME is active, device will require DMA bounce buffers\n");
-}
-
 int dma_supported(struct device *dev, u64 mask)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
@@ -327,7 +321,6 @@ int dma_set_mask(struct device *dev, u64 mask)
 		return -EIO;
 
 	arch_dma_set_mask(dev, mask);
-	dma_check_mask(dev, mask);
 	*dev->dma_mask = mask;
 	return 0;
 }
@@ -345,7 +338,6 @@ int dma_set_coherent_mask(struct device *dev, u64 mask)
 	if (!dma_supported(dev, mask))
 		return -EIO;
 
-	dma_check_mask(dev, mask);
 	dev->coherent_dma_mask = mask;
 	return 0;
 }