drm/vc4: hdmi: unlock mutex when device is unplugged

In vc4_hdmi_encoder_{pre,post}_crtc_enable() commit cd00ed51
("drm/vc4: hdmi: Protect device resources after removal") missed to
unlock the mutex before returning due to drm_dev_enter() indicating the
device being unplugged.

Fixes: cd00ed51 ("drm/vc4: hdmi: Protect device resources after removal")
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://lore.kernel.org/r/20220824161327.330627-2-dakr@redhat.com

drivers/gpu/drm/vc4/vc4_hdmi.c

@@ -1425,7 +1425,7 @@ static void vc4_hdmi_encoder_pre_crtc_enable(struct drm_encoder *encoder,
 	mutex_lock(&vc4_hdmi->mutex);
 
 	if (!drm_dev_enter(drm, &idx))
-		return;
+		goto out;
 
 	if (vc4_hdmi->variant->csc_setup)
 		vc4_hdmi->variant->csc_setup(vc4_hdmi, conn_state, mode);
@@ -1436,6 +1436,7 @@ static void vc4_hdmi_encoder_pre_crtc_enable(struct drm_encoder *encoder,
 
 	drm_dev_exit(idx);
 
+out:
 	mutex_unlock(&vc4_hdmi->mutex);
 }
 
@@ -1455,7 +1456,7 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 	mutex_lock(&vc4_hdmi->mutex);
 
 	if (!drm_dev_enter(drm, &idx))
-		return;
+		goto out;
 
 	spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
 
@@ -1516,6 +1517,8 @@ static void vc4_hdmi_encoder_post_crtc_enable(struct drm_encoder *encoder,
 	vc4_hdmi_enable_scrambling(encoder);
 
 	drm_dev_exit(idx);
+
+out:
 	mutex_unlock(&vc4_hdmi->mutex);
 }