Set Init patch HP to lowest frequency (6.875Hz)

Fixes surge-synthesizer#414 

This changes the Generic HighPass Filter (that is applied whether F1 or F2 are on or off) from 50Hz to minimum, which is 6.875Hz.

Former-commit-id: 9da8efdc2991a5c88892623612c2712668f7df97 [formerly 3f1726d]
Former-commit-id: 1418e83d6c3a4f50dd5eb6ef8c7491dcb53c5328
Former-commit-id: 71eb0adb65ca401c5413f1a5dade6a3af565727e

src/common/SurgePatch.cpp

@@ -587,7 +587,7 @@ void SurgePatch::init_default_values()
       scene[sc].route_noise.val.i = 1;
       scene[sc].pbrange_up.val.i = 2.f;
       scene[sc].pbrange_dn.val.i = 2.f;
-      scene[sc].lowcut.val.f = -36; // scene[sc].lowcut.val_min.f;
+      scene[sc].lowcut.val.f = scene[sc].lowcut.val_min.f;
       scene[sc].lowcut.per_voice_processing = false;
 
       scene[sc].adsr[0].a.val.f = scene[sc].adsr[0].a.val_min.f;