drm/sde: set DisplayPort/HDMI switch

Select DisplayPort or HDMI interface for audio based on which
interface is being enabled. This enables the audio engine to
send the audio data to correct interface.

CRs-Fixed: 2020938
Change-Id: I80fc7d4f7dd0427a5b003b85674344669bc258c6
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>