disp: msm: dp: fix locking during link maintenance

Ensure that session lock is held while handling link maintenance
to ensure that connect/disconnect handling and link maintenance are
serialized. This will avoid un-intended interleaving of session
setup/teardown with link maintenance which can result in link training
failures.

Change-Id: I96bb5b01a80433e26d675a019b8827de9fecb75b
Signed-off-by: Aravind Venkateswaran <aravindh@codeaurora.org>
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>

msm/dp/dp_display.c

@@ -1333,7 +1333,6 @@ static void dp_display_attention_work(struct work_struct *work)
 
 		mutex_lock(&dp->session_lock);
 		dp_audio_enable(dp, false);
-		mutex_unlock(&dp->session_lock);
 
 		if (dp->link->sink_request & DP_TEST_LINK_PHY_TEST_PATTERN) {
 			SDE_EVT32_EXTERNAL(dp->state,
@@ -1352,7 +1351,6 @@ static void dp_display_attention_work(struct work_struct *work)
 			dp->ctrl->link_maintenance(dp->ctrl);
 		}
 
-		mutex_lock(&dp->session_lock);
 		dp_audio_enable(dp, true);
 		mutex_unlock(&dp->session_lock);