MIPS: mm: remove mips_dma_mapping_error

dma_mapping_error() already checks if ops->mapping_error is a null
pointer

Signed-off-by: Felix Fietkau <nbd@nbd.name>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17881/
Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/mm/dma-default.c

@@ -373,11 +373,6 @@ static void mips_dma_sync_sg_for_device(struct device *dev,
 	}
 }
 
-static int mips_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
-{
-	return 0;
-}
-
 static int mips_dma_supported(struct device *dev, u64 mask)
 {
 	return plat_dma_supported(dev, mask);
@@ -404,7 +399,6 @@ static const struct dma_map_ops mips_default_dma_map_ops = {
 	.sync_single_for_device = mips_dma_sync_single_for_device,
 	.sync_sg_for_cpu = mips_dma_sync_sg_for_cpu,
 	.sync_sg_for_device = mips_dma_sync_sg_for_device,
-	.mapping_error = mips_dma_mapping_error,
 	.dma_supported = mips_dma_supported,
 	.cache_sync = mips_dma_cache_sync,
 };