ASoC: rk3399_gru_sound: Map BTN_0 to KEY_PLAYPAUSE

The Android 3.5mm Headset jack specification mentions that BTN_0 should
be mapped to KEY_MEDIA, but this is less logical than KEY_PLAYPAUSE,
which has much broader userspace support.

For example, the Chrome OS userspace now supports KEY_PLAYPAUSE to toggle
play/pause of videos and audio, but does not handle KEY_MEDIA.

Furthermore, Android itself now supports KEY_PLAYPAUSE equivalently, as the
new USB headset spec requires KEY_PLAYPAUSE for BTN_0.
https://source.android.com/devices/accessories/headset/usb-headset-specSigned-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/rockchip/rk3399_gru_sound.c

@@ -206,7 +206,8 @@ static int rockchip_sound_da7219_init(struct snd_soc_pcm_runtime *rtd)
 		return ret;
 	}
 
-	snd_jack_set_key(rockchip_sound_jack.jack, SND_JACK_BTN_0, KEY_MEDIA);
+	snd_jack_set_key(
+		rockchip_sound_jack.jack, SND_JACK_BTN_0, KEY_PLAYPAUSE);
 	snd_jack_set_key(
 		rockchip_sound_jack.jack, SND_JACK_BTN_1, KEY_VOLUMEUP);
 	snd_jack_set_key(