clk: Rename clk_get_by_driver_info()

This is actually a misnomer now, since the phandle info may contain
a driver_info index or a udevice index. Rename it to use the word
'phandle', which seems more accurate. Add a comment while we are here.

Also add a test for this function.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/clk/clk-uclass.c b/drivers/clk/clk-uclass.c
index 7b1ea07..493018b 100644
--- a/drivers/clk/clk-uclass.c
+++ b/drivers/clk/clk-uclass.c
@@ -36,8 +36,8 @@
 }
 
 #if CONFIG_IS_ENABLED(OF_PLATDATA)
-int clk_get_by_driver_info(struct udevice *dev, struct phandle_1_arg *cells,
-			   struct clk *clk)
+int clk_get_by_phandle(struct udevice *dev, const struct phandle_1_arg *cells,
+		       struct clk *clk)
 {
 	int ret;
 
@@ -413,6 +413,7 @@
 
 	return clk_get_by_index(dev, index, clk);
 }
+#endif /* OF_REAL */
 
 int clk_get_by_name_nodev(ofnode node, const char *name, struct clk *clk)
 {
@@ -465,8 +466,6 @@
 	return 0;
 }
 
-#endif /* OF_REAL */
-
 int clk_request(struct udevice *dev, struct clk *clk)
 {
 	const struct clk_ops *ops;