platform/x86: asus-wmi: Convert all attr-show to use sysfs_emit

This changes all *_show attributes in asus-wmi.c to use sysfs_emit()
instead of the older method of writing to the output buffer manually.

Signed-off-by: Luke D. Jones <luke@ljones.dev>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20220809025054.1626339-6-luke@ljones.dev


Signed-off-by: Hans de Goede <hdegoede@redhat.com>