MIPS: Remove unnecessary platform dma helper functions

The semantics stay the same - on Cavium Octeon the functions were dead
code (it overrides the MIPS DMA ops) - on other platforms they contained
no code at all.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5720/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
index 5f8b955..2e94185 100644
--- a/arch/mips/mm/dma-default.c
+++ b/arch/mips/mm/dma-default.c
@@ -297,7 +297,6 @@
 static void mips_dma_sync_single_for_device(struct device *dev,
 	dma_addr_t dma_handle, size_t size, enum dma_data_direction direction)
 {
-	plat_extra_sync_for_device(dev);
 	if (!plat_device_is_coherent(dev))
 		__dma_sync(dma_addr_to_page(dev, dma_handle),
 			   dma_handle & ~PAGE_MASK, size, direction);
@@ -327,7 +326,7 @@
 
 int mips_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
 {
-	return plat_dma_mapping_error(dev, dma_addr);
+	return 0;
 }
 
 int mips_dma_supported(struct device *dev, u64 mask)
@@ -340,7 +339,6 @@
 {
 	BUG_ON(direction == DMA_NONE);
 
-	plat_extra_sync_for_device(dev);
 	if (!plat_device_is_coherent(dev))
 		__dma_sync_virtual(vaddr, size, direction);
 }