ALSA: pxa2xx: Use guard() for mutex locks

Replace the manual mutex lock/unlock pairs with guard() for code
simplification.

Only code refactoring, and no behavior change.

Signed-off-by: Takashi Iwai <[e-mail]>
Link: https://patch.msgid.link/[e-mail]

sound/arm/pxa2xx-ac97-lib.c

···
 	if (slot > 0)
 		return -ENODEV;
 
-	mutex_lock(&car_mutex);
+	guard(mutex)(&car_mutex);
 
 	/* set up primary or secondary codec space */
 	if (cpu_is_pxa25x() && reg == AC97_GPIO_STATUS)
···
 	gsr_bits = 0;
 	val = (readl(reg_addr) & 0xffff);
 	if (reg == AC97_GPIO_STATUS)
-		goto out;
+		return val;
 	if (wait_event_timeout(gsr_wq, (readl(ac97_reg_base + GSR) | gsr_bits) & GSR_SDONE, 1) <= 0 &&
 	    !((readl(ac97_reg_base + GSR) | gsr_bits) & GSR_SDONE)) {
 		printk(KERN_ERR "%s: read error (ac97_reg=%d GSR=%#lx)\n",
 				__func__, reg, readl(ac97_reg_base + GSR) | gsr_bits);
-		val = -ETIMEDOUT;
-		goto out;
+		return -ETIMEDOUT;
 	}
 
 	/* valid data now */
···
 	val = (readl(reg_addr) & 0xffff);
 	/* but we've just started another cycle... */
 	wait_event_timeout(gsr_wq, (readl(ac97_reg_base + GSR) | gsr_bits) & GSR_SDONE, 1);
-
-out:	mutex_unlock(&car_mutex);
 	return val;
 }
 EXPORT_SYMBOL_GPL(pxa2xx_ac97_read);
···
 	u32 __iomem *reg_addr;
 	int ret = 0;
 
-	mutex_lock(&car_mutex);
+	guard(mutex)(&car_mutex);
 
 	/* set up primary or secondary codec space */
 	if (cpu_is_pxa25x() && reg == AC97_GPIO_STATUS)
···
 		ret = -EIO;
 	}
 
-	mutex_unlock(&car_mutex);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(pxa2xx_ac97_write);