[SCSI] sym2: Use DMA_40BIT_MASK constant

Now that this constant has been added to dma-mapping.h, we don't need our
own definition

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/sym53c8xx_2/sym_glue.c

@@ -1532,7 +1532,7 @@ static int sym_setup_bus_dma_mask(struct sym_hcb *np)
 {
 #if SYM_CONF_DMA_ADDRESSING_MODE > 0
 #if   SYM_CONF_DMA_ADDRESSING_MODE == 1
-#define	DMA_DAC_MASK	0x000000ffffffffffULL /* 40-bit */
+#define	DMA_DAC_MASK	DMA_40BIT_MASK
 #elif SYM_CONF_DMA_ADDRESSING_MODE == 2
 #define	DMA_DAC_MASK	DMA_64BIT_MASK
 #endif