drivers/dma/mmp_tdma.c: use gen_pool_dma_alloc() to allocate descriptor

Since gen_pool_dma_alloc() is introduced, we implement it to simplify code.
Signed-off-by: Nicolin Chen <b42378@freescale.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: Grant Likely <grant.likely@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/dma/mmp_tdma.c

@@ -350,12 +350,7 @@ struct mmp_tdma_desc *mmp_tdma_alloc_descriptor(struct mmp_tdma_chan *tdmac)
 	if (!gpool)
 		return NULL;
 
-	tdmac->desc_arr = (void *)gen_pool_alloc(gpool, size);
-	if (!tdmac->desc_arr)
-		return NULL;
-
-	tdmac->desc_arr_phys = gen_pool_virt_to_phys(gpool,
-			(unsigned long)tdmac->desc_arr);
+	tdmac->desc_arr = gen_pool_dma_alloc(gpool, size, &tdmac->desc_arr_phys);
 
 	return tdmac->desc_arr;
 }