firewire: Convert snprintf/sprintf to sysfs_emit

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.com
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>