ASoC: atmel: test wrong variable

After clk_get() mclk is checked second time instead of pllb check.
In patch v1 Jarkko Nikula noticed that PTR_ERR() is also has wrong argument.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/atmel/sam9g20_wm8731.c

@@ -222,9 +222,9 @@ static int __init at91sam9g20ek_init(void)
 	}
 
 	pllb = clk_get(NULL, "pllb");
-	if (IS_ERR(mclk)) {
+	if (IS_ERR(pllb)) {
 		printk(KERN_ERR "ASoC: Failed to get PLLB\n");
-		ret = PTR_ERR(mclk);
+		ret = PTR_ERR(pllb);
 		goto err_mclk;
 	}
 	ret = clk_set_parent(mclk, pllb);