ASoC: Intel: kbl_da7219_max98357a: Map BTN_0 to KEY_PLAYPAUSE

ASoC: Intel: kbl_da7219_max98357a: Map BTN_0 to KEY_PLAYPAUSE

On kbl_rt5663_max98927, commit 38a5882e4292
    ("ASoC: Intel: kbl_rt5663_max98927: Map BTN_0 to KEY_PLAYPAUSE")
    This key pair mapping to play/pause when playing Youtube

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-spec

The same fix is required on Chrome kbl_da7219_max98357a.

Signed-off-by: Mac Chiang <mac.chiang@intel.com>
Reviewed-by: Benson Leung <bleung@chromium.org>
Acked-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>