pci: Fix comment in struct pci_child_platdata

This is platdata, not private data, so the comment is currently incorrect.
Fix it to avoid confusion.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/include/pci.h b/include/pci.h
index dd5f051..936cfe9 100644
--- a/include/pci.h
+++ b/include/pci.h
@@ -822,7 +822,7 @@
  *
  * Every device on a PCI bus has this per-child data.
  *
- * It can be accessed using dev_get_parent_priv(dev) if dev->parent is a
+ * It can be accessed using dev_get_parent_platdata(dev) if dev->parent is a
  * PCI bus (i.e. UCLASS_PCI)
  *
  * @devfn:	Encoded device and function index - see PCI_DEVFN()