ACPI/thermal : Remove zone disabled warning

Once thermal zone is disabled to move thermal control to user space,
too many warnings printed in logs. Remove pr_warn from this path,
instead warn when user mode issues request to disable thermal zone.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Acked-by: Eduardo Valentin <eduardo.valentin@ti.com>
Signed-off-by: Zhang Rui <rui.zhang@intel.com>