tweaked i2c timings

haven't verified against a scope but they "work for me"

running at 24MHz at all times now for best energy use per watt before sleeping

firmware/app/led/matrix.c

@@ -29,7 +29,7 @@ uint8_t awled_fade[AW20X_FADE_COUNT];
 static uint8_t led_matrix_needs_update = 0;
 
 const LedMap led_map = {
-    // map is 1-based to match part numbers on the board
+    // map is 1-based to match LED refdegs on the board
     .ribbon = { // ribbon
         13, 25, 1, 49,
         37, 14,
@@ -71,6 +71,7 @@ const LedMap led_map = {
     }
 };
 
+
 LedMap led_set;