ASoC: samsung: smdk_wm8994: Fix build error

Fixes the following build error and warning when OF is not defined:
sound/soc/samsung/smdk_wm8994.c:191:23: error: ‘samsung_wm8994_of_match’ undeclared (first use in this function)
sound/soc/samsung/smdk_wm8994.c:47:32: warning: ‘smdk_board_data’ defined but not used [-Wunused-variable]

of_match_ptr() is used so that samsung_wm8994_of_match gets dropped (as unused)
by the compiler when OF is not defined.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/samsung/smdk_wm8994.c

@@ -152,13 +152,11 @@ static struct snd_soc_card smdk = {
 	.num_links = ARRAY_SIZE(smdk_dai),
 };
 
-#ifdef CONFIG_OF
 static const struct of_device_id samsung_wm8994_of_match[] = {
 	{ .compatible = "samsung,smdk-wm8994", .data = &smdk_board_data },
 	{},
 };
 MODULE_DEVICE_TABLE(of, samsung_wm8994_of_match);
-#endif /* CONFIG_OF */
 
 static int smdk_audio_probe(struct platform_device *pdev)
 {
@@ -188,7 +186,7 @@ static int smdk_audio_probe(struct platform_device *pdev)
 		smdk_dai[0].platform_of_node = smdk_dai[0].cpu_of_node;
 	}
 
-	id = of_match_device(samsung_wm8994_of_match, &pdev->dev);
+	id = of_match_device(of_match_ptr(samsung_wm8994_of_match), &pdev->dev);
 	if (id)
 		*board = *((struct smdk_wm8994_data *)id->data);