mtd: spi-nor: cadence-quadspi: Use proper enum for dma_[un]map_single

Clang warns when one enumerated type is converted implicitly to another.

drivers/mtd/spi-nor/cadence-quadspi.c:962:47: warning: implicit
conversion from enumeration type 'enum dma_transfer_direction' to
different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
        dma_dst = dma_map_single(nor->dev, buf, len, DMA_DEV_TO_MEM);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
./include/linux/dma-mapping.h:428:66: note: expanded from macro
'dma_map_single'
                                   ~~~~~~~~~~~~~~~~~~~~          ^
drivers/mtd/spi-nor/cadence-quadspi.c:997:43: warning: implicit
conversion from enumeration type 'enum dma_transfer_direction' to
different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
        dma_unmap_single(nor->dev, dma_dst, len, DMA_DEV_TO_MEM);
        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
./include/linux/dma-mapping.h:429:70: note: expanded from macro
'dma_unmap_single'
                                     ~~~~~~~~~~~~~~~~~~~~~~          ^
2 warnings generated.

Use the proper enums from dma_data_direction to satisfy Clang.

DMA_FROM_DEVICE = DMA_DEV_TO_MEM = 2

Link: ClangBuiltLinux/linux#108
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>

drivers/mtd/spi-nor/cadence-quadspi.c

@@ -959,7 +959,7 @@ static int cqspi_direct_read_execute(struct spi_nor *nor, u_char *buf,
 		return 0;
 	}
 
-	dma_dst = dma_map_single(nor->dev, buf, len, DMA_DEV_TO_MEM);
+	dma_dst = dma_map_single(nor->dev, buf, len, DMA_FROM_DEVICE);
 	if (dma_mapping_error(nor->dev, dma_dst)) {
 		dev_err(nor->dev, "dma mapping failed\n");
 		return -ENOMEM;
@@ -994,7 +994,7 @@ static int cqspi_direct_read_execute(struct spi_nor *nor, u_char *buf,
 	}
 
 err_unmap:
-	dma_unmap_single(nor->dev, dma_dst, len, DMA_DEV_TO_MEM);
+	dma_unmap_single(nor->dev, dma_dst, len, DMA_FROM_DEVICE);
 
 	return 0;
 }