ACPI thermal: remove deprecated procfs I/F

Remove the deprecated ACPI thermal driver procfs I/F,
as stated in the changelog of commit 43d9f87b

sysfs I/F is available at /sys/class/thermal/thermal_zoneX/

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>