drm/stm: ltdc: Fix leak of px clk enable in some error paths

The pixel clock gets enabled early during init, since it's required
in order to read registers. This pixel clock must be disabled if
errors during this init phase.
Signed-off-by: Eric Anholt <eric@anholt.net>
Acked-by: Philippe Cornu <philippe.cornu@st.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1500277223-29553-2-git-send-email-philippe.cornu@st.com

drivers/gpu/drm/stm/ltdc.c

@@ -1045,13 +1045,15 @@ int ltdc_load(struct drm_device *ddev)
 
 	if (of_address_to_resource(np, 0, &res)) {
 		DRM_ERROR("Unable to get resource\n");
-		return -ENODEV;
+		ret = -ENODEV;
+		goto err;
 	}
 
 	ldev->regs = devm_ioremap_resource(dev, &res);
 	if (IS_ERR(ldev->regs)) {
 		DRM_ERROR("Unable to get ltdc registers\n");
-		return PTR_ERR(ldev->regs);
+		ret = PTR_ERR(ldev->regs);
+		goto err;
 	}
 
 	for (i = 0; i < MAX_IRQ; i++) {
@@ -1064,7 +1066,7 @@ int ltdc_load(struct drm_device *ddev)
 						dev_name(dev), ddev);
 		if (ret) {
 			DRM_ERROR("Failed to register LTDC interrupt\n");
-			return ret;
+			goto err;
 		}
 	}
 
@@ -1079,7 +1081,7 @@ int ltdc_load(struct drm_device *ddev)
 	if (ret) {
 		DRM_ERROR("hardware identifier (0x%08x) not supported!\n",
 			  ldev->caps.hw_version);
-		return ret;
+		goto err;
 	}
 
 	DRM_INFO("ltdc hw version 0x%08x - ready\n", ldev->caps.hw_version);