Fix light level values array.

src/main.c

@@ -60,7 +60,7 @@ static const uint8_t PROGMEM brightConv[BRIGHT_IDX_MAX+1] = {
 #if F_CPU == 16000000
   155, 164, 181, 211, 255
 #elif F_CPU == 8000000
-  117, 151, 185, 219, 255
+  88, 102, 131, 180, 255
 #endif // F_CPU
 };
 #endif // USE_BRIGHT_CONTROL