clocksource: sun4i: Don't forget to enable the clock we use

Even if in our case, this clock was non-gatable, used as a parent clock
for several IPs, it still is a good idea to enable it.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

drivers/clocksource/sun4i_timer.c

@@ -120,6 +120,7 @@ static void __init sun4i_timer_init(struct device_node *node)
 	clk = of_clk_get(node, 0);
 	if (IS_ERR(clk))
 		panic("Can't get timer clock");
+	clk_prepare_enable(clk);
 
 	rate = clk_get_rate(clk);