Use MediaFormat constant for MIME type

Replace "video/avc" by MIMETYPE_VIDEO_AVC.

Signed-off-by: Romain Vimont <rom@rom1v.com>

server/src/main/java/com/genymobile/scrcpy/ScreenEncoder.java

@@ -136,12 +136,12 @@ public class ScreenEncoder implements Device.RotationListener {
     }
 
     private static MediaCodec createCodec() throws IOException {
-        return MediaCodec.createEncoderByType("video/avc");
+        return MediaCodec.createEncoderByType(MediaFormat.MIMETYPE_VIDEO_AVC);
     }
 
     private static MediaFormat createFormat(int bitRate, int maxFps, int iFrameInterval) {
         MediaFormat format = new MediaFormat();
-        format.setString(MediaFormat.KEY_MIME, "video/avc");
+        format.setString(MediaFormat.KEY_MIME, MediaFormat.MIMETYPE_VIDEO_AVC);
         format.setInteger(MediaFormat.KEY_BIT_RATE, bitRate);
         // must be present to configure the encoder, but does not impact the actual frame rate, which is variable
         format.setInteger(MediaFormat.KEY_FRAME_RATE, 60);