disp: msm: dp: skip wait if audio engine is disabled

Skip the wait in the disable path if the audio engine has already
been disabled or was not previously enabled. This avoids an
unnecessary wait since the audio subsystem will only acknowledge
the notification and not request a tear down if no audio playback
was started by the user.

CRs-Fixed: 2550150
Change-Id: I7b47345430f3d9c63b80b0aa92cdc4dd77152da9
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>