The clock is not unprepared in case of the request IRQ fails.

Also update to request_irq.
Signed-off-by: NGaël PORTAY <gael.portay@gmail.com>
Acked-by: NDaniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: NBoris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: NDaniel Lezcano <daniel.lezcano@linaro.org>