clk: add support for clk_is_match()

Add support for clk_is_match() which is required to
know if two clock pointers point to the same exact
physical clock.

Also add a unit test for the new API.

Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>

drivers/clk/clk-uclass.c

@@ -518,6 +518,19 @@ int clk_get_by_id(ulong id, struct clk **clkp)
 	return -ENOENT;
 }
 
+bool clk_is_match(const struct clk *p, const struct clk *q)
+{
+	/* trivial case: identical struct clk's or both NULL */
+	if (p == q)
+		return true;
+
+	/* same device, id and data */
+	if (p->dev == q->dev && p->id == q->id && p->data == q->data)
+		return true;
+
+	return false;
+}
+
 UCLASS_DRIVER(clk) = {
 	.id		= UCLASS_CLK,
 	.name		= "clk",