platform/chrome: use sysfs_emit() instead of scnprintf()

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: ye xingchen <ye.xingchen@zte.com.cn>
Link: https://lore.kernel.org/r/202212021656040995199@zte.com.cn


[tzungbi: fixed the commit message.]
Signed-off-by: Tzung-Bi Shih <tzungbi@kernel.org>