firewire: Convert snprintf/sprintf to sysfs_emit

Per filesystems/sysfs.rst, show() should only use sysfs_emit()
or sysfs_emit_at() when formatting the value to be returned to user space.

coccinelle complains that there are still a couple of functions that use
snprintf(). Convert them to sysfs_emit().

> drivers/firewire/core-device.c:326:8-16: WARNING: please use sysfs_emit or sysfs_emit_at

No functional change intended
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Link: https://lore.kernel.org/r/20240122053942.80648-2-lizhijian@fujitsu.comSigned-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

drivers/firewire/core-device.c

@@ -322,7 +322,7 @@ static ssize_t show_immediate(struct device *dev,
 	if (value < 0)
 		return -ENOENT;
 
-	return snprintf(buf, PAGE_SIZE, "0x%06x\n", value);
+	return sysfs_emit(buf, "0x%06x\n", value);
 }
 
 #define IMMEDIATE_ATTR(name, key)				\
@@ -482,7 +482,7 @@ static ssize_t is_local_show(struct device *dev,
 {
 	struct fw_device *device = fw_device(dev);
 
-	return sprintf(buf, "%u\n", device->is_local);
+	return sysfs_emit(buf, "%u\n", device->is_local);
 }
 
 static int units_sprintf(char *buf, const u32 *directory)