dmaengine: constify of_device_id array

of_device_id is always used as const.
(See driver.of_match_table and open firmware functions)

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
diff --git a/drivers/dma/sirf-dma.c b/drivers/dma/sirf-dma.c
index d0086e9..a1afda4 100644
--- a/drivers/dma/sirf-dma.c
+++ b/drivers/dma/sirf-dma.c
@@ -896,7 +896,7 @@
 	SET_SYSTEM_SLEEP_PM_OPS(sirfsoc_dma_pm_suspend, sirfsoc_dma_pm_resume)
 };
 
-static struct of_device_id sirfsoc_dma_match[] = {
+static const struct of_device_id sirfsoc_dma_match[] = {
 	{ .compatible = "sirf,prima2-dmac", },
 	{ .compatible = "sirf,marco-dmac", },
 	{},