tuning: print executed toggle script

report executed toggle_script back to user via ui_notify_user().

Example:
 >> 'auto' > '/sys/bus/pci/devices/0000:00:1c.1/power/control';
 >> echo 'on' > '/sys/bus/pci/devices/0000:00:1c.1/power/control';

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>