ACPI: sysfs: use sysfs_emit() to instead of scnprintf()

Replace scnprintf() with sysfs_emit() to simplify the code.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: Yang Yang <yang.yang29@zte.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>