msm: mdss: hdmi: notify audio switch device only for CEA resolutions

Upon successful connection, audio should switch over to HDMI only for
CEA resolutions. In the current implementation, when HDCP authentication
succeeds, the audio switch device is notified irrespective of the
selected resolution even though no audio related setup is done. This can
lead to unintended consequences during video playback. Fix this by
notifying the audio switch device only for CEA resolutions.

Change-Id: If1372c0d6171d6d8091a768462043bffc41109d1
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>