core: return FDT_ADDR_T_NONE from devfdt_get_addr_[size_]name() on errors

Checking for the error cast to fdt_addr_t is rather awkward - IS_ERR()
can be used, but it's not really made to be used on fdt_addr_t, which
may not even be the same size as a native pointer.

Most places in U-Boot only check for FDT_ADDR_T_NONE; let's adjust the
error return to match the expectation.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/fdtaddr.c b/drivers/core/fdtaddr.c
index b79d138..0f4eff6 100644
--- a/drivers/core/fdtaddr.c
+++ b/drivers/core/fdtaddr.c
@@ -145,7 +145,7 @@
 	index = fdt_stringlist_search(gd->fdt_blob, dev_of_offset(dev),
 				      "reg-names", name);
 	if (index < 0)
-		return index;
+		return FDT_ADDR_T_NONE;
 
 	return devfdt_get_addr_index(dev, index);
 #else
@@ -162,7 +162,7 @@
 	index = fdt_stringlist_search(gd->fdt_blob, dev_of_offset(dev),
 				      "reg-names", name);
 	if (index < 0)
-		return index;
+		return FDT_ADDR_T_NONE;
 
 	return devfdt_get_addr_size_index(dev, index, size);
 #else
diff --git a/include/dm/fdtaddr.h b/include/dm/fdtaddr.h
index 5e8eafc..c577d43 100644
--- a/include/dm/fdtaddr.h
+++ b/include/dm/fdtaddr.h
@@ -142,7 +142,7 @@
  *	  'reg-names' property providing named-based identification. @name
  *	  indicates the value to search for in 'reg-names'.
  *
- * Return: addr
+ * Return: Address, or FDT_ADDR_T_NONE if there is no such property
  */
 fdt_addr_t devfdt_get_addr_name(const struct udevice *dev, const char *name);
 
@@ -159,7 +159,7 @@
  * @size: Pointer to size variable - this function returns the size
  *        specified in the 'reg' property here
  *
- * Return: addr
+ * Return: Address, or FDT_ADDR_T_NONE if there is no such property
  */
 fdt_addr_t devfdt_get_addr_size_name(const struct udevice *dev,
 				     const char *name, fdt_size_t *size);