Added SineOutTest in AK4558 Examples folder

The test puts a 440 Hz sinewave on one channel, and a 220 Hz on the
other

examples/HardwareTesting/AK4558/SineOutTest/SineOutTest.ino

@@ -0,0 +1,30 @@
+#include <Audio.h>
+#include <Wire.h>
+#include <SPI.h>
+#include <SD.h>
+#include <SerialFlash.h>
+
+// GUItool: begin automatically generated code
+AudioSynthWaveformSine   sine2;          //xy=309,245
+AudioSynthWaveformSine   sine1;          //xy=320,133
+AudioOutputI2S           i2s2;           //xy=460,178
+AudioConnection          patchCord1(sine2, 0, i2s2, 1);
+AudioConnection          patchCord2(sine1, 0, i2s2, 0);
+AudioControlAK4558       ak4558;       //xy=172,178
+// GUItool: end automatically generated code
+
+void setup() {
+  // put your setup code here, to run once:
+  sine1.frequency(440);
+  sine2.frequency(220);
+  sine1.amplitude(1.0);
+  sine2.amplitude(1.0);
+  delay(10000);
+  Serial.begin(9600);
+  Serial.println("test");
+  ak4558.enable();
+}
+
+void loop() {
+  delay(1);
+}