usb: dwc3: fix memory leak of dwc->regset

dwc->regset is allocated on dwc3_debugfs_init, and should
be released on init failure or dwc3_debugfs_exit. Btw,
The line "dwc->root = NULL" is unnecessary, so remove it.
Signed-off-by: NDu, Changbin <changbin.du@intel.com>

[ felipe.balbi@linux.intel.com : add another err label for the new
	error condition ]
Signed-off-by: NFelipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/debugfs.c

@@ -645,7 +645,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 	file = debugfs_create_regset32("regdump", S_IRUGO, root, dwc->regset);
 	if (!file) {
 		ret = -ENOMEM;
-		goto err1;
+		goto err2;
 	}
 
 	if (IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)) {
@@ -653,7 +653,7 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 				dwc, &dwc3_mode_fops);
 		if (!file) {
 			ret = -ENOMEM;
-			goto err1;
+			goto err2;
 		}
 	}
 
@@ -663,19 +663,22 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 				dwc, &dwc3_testmode_fops);
 		if (!file) {
 			ret = -ENOMEM;
-			goto err1;
+			goto err2;
 		}
 
 		file = debugfs_create_file("link_state", S_IRUGO | S_IWUSR, root,
 				dwc, &dwc3_link_state_fops);
 		if (!file) {
 			ret = -ENOMEM;
-			goto err1;
+			goto err2;
 		}
 	}
 
 	return 0;
 
+err2:
+	kfree(dwc->regset);
+
 err1:
 	debugfs_remove_recursive(root);
 
@@ -686,5 +689,5 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 void dwc3_debugfs_exit(struct dwc3 *dwc)
 {
 	debugfs_remove_recursive(dwc->root);
-	dwc->root = NULL;
+	kfree(dwc->regset);
 }