Use private area Unicode for spectrum visualizer

Please note this will work properly only with my patched terminus font
available at

squash

src/screens/visualizer.cpp

@@ -83,8 +83,8 @@ Visualizer::Visualizer()
   HZ_MIN(Config.visualizer_spectrum_hz_min),
   HZ_MAX(Config.visualizer_spectrum_hz_max),
   GAIN(Config.visualizer_spectrum_gain),
-  SMOOTH_CHARS(ToWString("▁▂▃▄▅▆▇█")),
-  SMOOTH_CHARS_FLIPPED(ToWString("▔🮂🮃🮄🬎🮅🮆█")) // https://unicode.org/charts/PDF/U1FB00.pdf
+  SMOOTH_CHARS(ToWString("")),
+  SMOOTH_CHARS_FLIPPED(ToWString(""))
 #endif
 {
 	InitDataSource();
@@ -535,12 +535,7 @@ void Visualizer::DrawFrequencySpectrum(const int16_t *buf, ssize_t samples, size
 				} else {
 					// fractional height
 					if (flipped) {
-						if (Config.visualizer_spectrum_smooth_look_legacy_chars) {
 						ch = SMOOTH_CHARS_FLIPPED[idx];
-						} else {
-							ch = SMOOTH_CHARS[size-idx-2];
-							color = NC::FormattedColor(color.color(), {NC::Format::Reverse});
-						}
 					} else {
 						ch = SMOOTH_CHARS[idx];
 					}