ASoC: cs35l56: Fix an unsigned comparison which can never be negative

The variable 'rv' is defined as unsigned type, so the following if
statement is invalid, we can modify the type of rv to int.
if (rv < 0) {
	dev_err(cs35l56->dev, "irq: failed to get pm_runtime:
		%d\n", rv);
	goto err_unlock;
}

./sound/soc/codecs/cs35l56.c:333:5-7: WARNING: Unsigned expression compared with zero: rv < 0.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=4599Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reviewed-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230324022303.121485-1-jiapeng.chong@linux.alibaba.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/cs35l56.c

@@ -321,7 +321,9 @@ irqreturn_t cs35l56_irq(int irq, void *data)
 	struct cs35l56_private *cs35l56 = data;
 	unsigned int status1 = 0, status8 = 0, status20 = 0;
 	unsigned int mask1, mask8, mask20;
-	unsigned int rv, val;
+	unsigned int val;
+	int rv;
+
 	irqreturn_t ret = IRQ_NONE;
 
 	if (!cs35l56->init_done)