INT 15 - Advanced Power Management Spec - ENABLE/DISABLE POWER MANAGEMENT
        AX = 5308h
        BX = FFFFh
        CX = new state
            0000h disabled
            0001h enabled
Return: CF clear if successful
        CF set on error
            AH = error code (01h,09h,0Ah) (see AX=5300h)
Notes:  when power management is disabled, the system BIOS will not
          automatically power down devices, enter stand-by or suspended mode,
          or perform any power-saving actions in response to AX=5305h calls
        should not be called from within a hardware interrupt handler to avoid
          reentrance problems