ptp: replace snprintf with sysfs_emit

coccinelle report:
./drivers/ptp/ptp_sysfs.c:17:8-16:
WARNING: use scnprintf or sprintf
./drivers/ptp/ptp_sysfs.c:390:8-16:
WARNING: use scnprintf or sprintf

Use sysfs_emit instead of scnprintf or sprintf makes more sense.

Reported-by: Zeal Robot <[e-mail]>
Signed-off-by: Yang Guang <[e-mail]>
Signed-off-by: David Yang <[e-mail]>
Acked-by: Richard Cochran <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/ptp/ptp_sysfs.c

···
 			       struct device_attribute *attr, char *page)
 {
 	struct ptp_clock *ptp = dev_get_drvdata(dev);
-	return snprintf(page, PAGE_SIZE-1, "%s\n", ptp->info->name);
+	return sysfs_emit(page, "%s\n", ptp->info->name);
 }
 static DEVICE_ATTR_RO(clock_name);
 
···
 
 	mutex_unlock(&ptp->pincfg_mux);
 
-	return snprintf(page, PAGE_SIZE, "%u %u\n", func, chan);
+	return sysfs_emit(page, "%u %u\n", func, chan);
 }
 
 static ssize_t ptp_pin_store(struct device *dev, struct device_attribute *attr,