Make AGC-T level consistent between Fast/Med/Slow and OFF.

Robert -- N5IKD

The AGC Threshold slider has a separate level when the AGC is set to Fast/Med/Slow than it does when the AGC is turned off. The problem comes when I turn down the AGC-T, then later turn off the AGC, BOOM, my speakers and ears are blown out. If I turn down the AGC-T with AGC on, then I want the threshold level to be the same when I turn the AGC off and vise versa.