Int 15 Fn BA21  - Hp Omnishare - Standby.com - Set Standby Duration        [p]

   AX = BA21h
   BL = new timeout before standby mode in minutes (01h-0Fh)
       00h to disable automatic switch to standby mode

Return: CF clear if successful
   CF set on error (function not supported)

Note:  The actual timeout with a GD6205 controller is ((N*64)-32) seconds,
     instead of (N*60) seconds as documented.

See Also: AX=BA20h,AX=BA22h