fdt_support: Fix comment for fdt_create_phandle()

This function does not necessarily create a new phandle. If a phandle
exists, no new phandle is created.

Signed-off-by: Marek BehĂșn <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/common/fdt_support.c b/common/fdt_support.c
index 8ac9050..df111f7 100644
--- a/common/fdt_support.c
+++ b/common/fdt_support.c
@@ -1504,7 +1504,7 @@
 }
 
 /*
- * fdt_create_phandle: Create a phandle property for the given node
+ * fdt_create_phandle: Get or create a phandle property for the given node
  *
  * @fdt: ptr to device tree
  * @nodeoffset: node to update