w1: core: use sysfs_emit() instead of sprintf()

Follow the advice in Documentation/filesystems/sysfs.rst:
show() should only use sysfs_emit() or sysfs_emit_at() when formatting
the value to be returned to user space.

Signed-off-by: zhangheng <zhangheng@kylinos.cn>
Link: https://lore.kernel.org/r/20241220102337.295864-1-zhangheng@kylinos.cn


Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>