media: mtk_vcodec_util: Use dma_zalloc_coherent to replace dma_alloc_coherent + memset

dma_zalloc_coherent has implemented the dma_alloc_coherent() + memset(),
We prefer to dma_zalloc_coherent instead of open-codeing.
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/mtk-vcodec/mtk_vcodec_util.c

@@ -49,16 +49,13 @@ int mtk_vcodec_mem_alloc(struct mtk_vcodec_ctx *data,
 	struct mtk_vcodec_ctx *ctx = (struct mtk_vcodec_ctx *)data;
 	struct device *dev = &ctx->dev->plat_dev->dev;
 
-	mem->va = dma_alloc_coherent(dev, size, &mem->dma_addr, GFP_KERNEL);
-
+	mem->va = dma_zalloc_coherent(dev, size, &mem->dma_addr, GFP_KERNEL);
 	if (!mem->va) {
 		mtk_v4l2_err("%s dma_alloc size=%ld failed!", dev_name(dev),
 			     size);
 		return -ENOMEM;
 	}
 
-	memset(mem->va, 0, size);
-
 	mtk_v4l2_debug(3, "[%d]  - va      = %p", ctx->id, mem->va);
 	mtk_v4l2_debug(3, "[%d]  - dma     = 0x%lx", ctx->id,
 		       (unsigned long)mem->dma_addr);