ofnode: add ofnode_by_prop_value()

Adds ofnode_by_prop_value() to search for nodes with a given property
and value, an ofnode version of fdt_node_offset_by_prop_value().

Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/core/ofnode.c b/drivers/core/ofnode.c
index 0cfb0fb..a7e1927 100644
--- a/drivers/core/ofnode.c
+++ b/drivers/core/ofnode.c
@@ -777,3 +777,17 @@
 				gd->fdt_blob, ofnode_to_offset(from), compat));
 	}
 }
+
+ofnode ofnode_by_prop_value(ofnode from, const char *propname,
+			    const void *propval, int proplen)
+{
+	if (of_live_active()) {
+		return np_to_ofnode(of_find_node_by_prop_value(
+			(struct device_node *)ofnode_to_np(from), propname,
+			propval, proplen));
+	} else {
+		return offset_to_ofnode(fdt_node_offset_by_prop_value(
+				gd->fdt_blob, ofnode_to_offset(from),
+				propname, propval, proplen));
+	}
+}