fix(fdt): avoid output on missing DT property

When we use our fdt_read_uint32* helper functions, we output a warning
on not finding the requested property.

However non-existing properties are not that uncommon, and *trying* to
read such a property is actually a nice way of checking its existence.

Since we already return a specific error value in this case, the caller
can easily check this and give a more specific error message, if needed.
When the caller decides to properly handle the error (fallback, default
value, etc), a message on the console is quite misleading.

Demote the message to a VERBOSE, so normal builds will not spam the
console with pointless messages.

Change-Id: I7a279a4ee0147c5f4a0503d0a8745c6cfea58be5
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/common/fdt_wrappers.c b/common/fdt_wrappers.c
index 64e01ea..cfa1342 100644
--- a/common/fdt_wrappers.c
+++ b/common/fdt_wrappers.c
@@ -35,7 +35,7 @@
 	/* Access property and obtain its length (in bytes) */
 	prop = fdt_getprop(dtb, node, prop_name, &value_len);
 	if (prop == NULL) {
-		WARN("Couldn't find property %s in dtb\n", prop_name);
+		VERBOSE("Couldn't find property %s in dtb\n", prop_name);
 		return -FDT_ERR_NOTFOUND;
 	}