[Unity] Fix incorrect evaluation of logarithmic distance curve.

Fixes: #343

unity/src/project/SteamAudioUnity/Assets/Plugins/SteamAudio/Scripts/Runtime/SteamAudioSource.cs

@@ -510,7 +510,7 @@ public static float EvaluateDistanceCurve(float distance, IntPtr userData)
                 case AudioRolloffMode.Logarithmic:
                     if (distance < rMin)
                         return 1.0f;
-                    else if (distance < rMax)
+                    else if (distance > rMax)
                         return 0.0f;
                     else
                         return rMin / distance;