ASoC: samsung-i2s: Check secondary DAI exists before referencing

commit 133c2681 upstream.

In a couple of places the driver is missing a check to ensure there is a
secondary DAI before it de-references the pointer to it, causing a null
pointer de-reference. This patch adds a check to avoid this.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
[lizf: Backported to 3.4: drop the changes to i2s_shutdown()]
Signed-off-by: Zefan Li <lizefan@huawei.com>

sound/soc/samsung/i2s.c

@@ -392,7 +392,7 @@ static int i2s_set_sysclk(struct snd_soc_dai *dai,
 		if (dir == SND_SOC_CLOCK_IN)
 			rfs = 0;
 
-		if ((rfs && other->rfs && (other->rfs != rfs)) ||
+		if ((rfs && other && other->rfs && (other->rfs != rfs)) ||
 				(any_active(i2s) &&
 				(((dir == SND_SOC_CLOCK_IN)
 					&& !(mod & MOD_CDCLKCON)) ||