drm: zynqmp_dp: Unlock on error in zynqmp_dp_bridge_atomic_enable()

We added some locking to this function, but accidentally forgot to unlock
if zynqmp_dp_mode_configure() failed.  Use a guard lock to fix it.

Fixes: a7d5eea ("drm: zynqmp_dp: Add locking")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Sean Anderson <sean.anderson@linux.dev>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b4042bd9-c943-4738-a2e1-8647259137c6@stanley.mountain

Author: Dan Carpenter

drivers/gpu/drm/xlnx/zynqmp_dp.c

@@ -1537,7 +1537,7 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 
 	pm_runtime_get_sync(dp->dev);
 
-	mutex_lock(&dp->lock);
+	guard(mutex)(&dp->lock);
 	zynqmp_dp_disp_enable(dp, old_bridge_state);
 
 	/*
@@ -1598,7 +1598,6 @@ static void zynqmp_dp_bridge_atomic_enable(struct drm_bridge *bridge,
 	zynqmp_dp_write(dp, ZYNQMP_DP_SOFTWARE_RESET,
 			ZYNQMP_DP_SOFTWARE_RESET_ALL);
 	zynqmp_dp_write(dp, ZYNQMP_DP_MAIN_STREAM_ENABLE, 1);
-	mutex_unlock(&dp->lock);
 }
 
 static void zynqmp_dp_bridge_atomic_disable(struct drm_bridge *bridge,