bus: ti-sysc: Fix getting optional clocks in clock_roles

We can have holes in clock_roles with interface clock missing for
example. Currently getting an optional clock will fail if there are
only a functional clock and an optional clock.

Fixes: 09dfe581 ("bus: ti-sysc: Add handling for clkctrl opt clocks")
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/bus/ti-sysc.c

@@ -214,8 +214,13 @@ static int sysc_get_clocks(struct sysc *ddata)
 	if (!ddata->clocks)
 		return -ENOMEM;
 
-	for (i = 0; i < ddata->nr_clocks; i++) {
-		error = sysc_get_one_clock(ddata, ddata->clock_roles[i]);
+	for (i = 0; i < SYSC_MAX_CLOCKS; i++) {
+		const char *name = ddata->clock_roles[i];
+
+		if (!name)
+			continue;
+
+		error = sysc_get_one_clock(ddata, name);
 		if (error && error != -ENOENT)
 			return error;
 	}