platform/x86: dell-wmi-sysman: Use standard kobj_sysfs_ops

wmi_sysman_kobj_sysfs_ops are identical to the standard kobj_sysfs_ops.

Drop the unnecessary custom copy.

Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20260223-sysfs-const-dell-wmi-sysman-v1-1-8a690884044e@weissschuh.net
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>