w1: w1_therm: use swap() to make code cleaner

Use the macro 'swap()' defined in 'include/linux/minmax.h' to avoid
opencoding it.
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: David Yang <davidcomponentone@gmail.com>
Signed-off-by: Yang Guang <yang.guang5@zte.com.cn>
Link: https://lore.kernel.org/r/cb14f9e6e86cf8494ed2ddce6eec8ebd988908d9.1640077704.git.yang.guang5@zte.com.cnSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/w1/slaves/w1_therm.c

@@ -1785,7 +1785,7 @@ static ssize_t alarms_store(struct device *device,
 	u8 new_config_register[3];	/* array of data to be written */
 	int temp, ret;
 	char *token = NULL;
-	s8 tl, th, tt;	/* 1 byte per value + temp ring order */
+	s8 tl, th;	/* 1 byte per value + temp ring order */
 	char *p_args, *orig;
 
 	p_args = orig = kmalloc(size, GFP_KERNEL);
@@ -1836,9 +1836,8 @@ static ssize_t alarms_store(struct device *device,
 	th = int_to_short(temp);
 
 	/* Reorder if required th and tl */
-	if (tl > th) {
-		tt = tl; tl = th; th = tt;
-	}
+	if (tl > th)
+		swap(tl, th);
 
 	/*
 	 * Read the scratchpad to change only the required bits