dmaengine: ti: omap-dma: Drop of_match_ptr to fix -Wunused-const-variable

The of_device_id is included unconditionally by of.h header and used
in the driver as well.  Remove of_match_ptr to fix W=1 compile test
warning with !CONFIG_OF:

    drivers/dma/ti/omap-dma.c:1892:34: warning: 'omap_dma_match' defined but not used [-Wunused-const-variable=]
     1892 | static const struct of_device_id omap_dma_match[] = {

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://lore.kernel.org/r/20200728170939.28278-1-krzk@kernel.org
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/ti/omap-dma.c

@@ -1904,7 +1904,7 @@ static struct platform_driver omap_dma_driver = {
 	.remove	= omap_dma_remove,
 	.driver = {
 		.name = "omap-dma-engine",
-		.of_match_table = of_match_ptr(omap_dma_match),
+		.of_match_table = omap_dma_match,
 	},
 };