ASoC: msm: 8974: Fix HDMI audio enable criteria

HDMI audio feature should be disabled if hdmi panel is not
enabled on the platform. This change ensures that HDMI audio
is enabled only when HDMI panel is present.

CRs-fixed: 476010
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>
Change-Id: I6779a9b2afa763b7a78b5e9f8be1f8b230298830