PCI/VGA: Simplify vga_client_register()

Reorganize vga_client_register() to avoid the goto and the need to save the
return value.  Update the kernel-doc to reflect -ENODEV on failure.  No
functional change intended.

[bhelgaas: drop "ret" variable, commit log]
Link: https://lore.kernel.org/r/20230808223412.1743176-8-sui.jingfeng@linux.dev
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

Author: Sui Jingfeng

drivers/pci/vgaarb.c

@@ -967,27 +967,22 @@ EXPORT_SYMBOL(vga_set_legacy_decoding);
  *
  * To unregister just call vga_client_unregister().
  *
- * Returns: 0 on success, -1 on failure
+ * Returns: 0 on success, -ENODEV on failure
  */
 int vga_client_register(struct pci_dev *pdev,
 		unsigned int (*set_decode)(struct pci_dev *pdev, bool decode))
 {
-	int ret = -ENODEV;
-	struct vga_device *vgadev;
 	unsigned long flags;
+	struct vga_device *vgadev;
 
 	spin_lock_irqsave(&vga_lock, flags);
 	vgadev = vgadev_find(pdev);
-	if (!vgadev)
-		goto bail;
-
-	vgadev->set_decode = set_decode;
-	ret = 0;
-
-bail:
+	if (vgadev)
+		vgadev->set_decode = set_decode;
 	spin_unlock_irqrestore(&vga_lock, flags);
-	return ret;
-
+	if (!vgadev)
+		return -ENODEV;
+	return 0;
 }
 EXPORT_SYMBOL(vga_client_register);