clocksource/drivers/bcm2835_timer: Fix memory leak of timer

Currently when setup_irq fails the error exit path will leak the
recently allocated timer structure. Originally the code would
throw a panic but a later commit changed the behaviour to return
via the err_iounmap path and hence we now have a memory leak. Fix
this by adding a err_timer_free error path that kfree's timer.

Addresses-Coverity: ("Resource Leak")
Fixes: 524a7f08983d ("clocksource/drivers/bcm2835_timer: Convert init function to return error")
Signed-off-by: Colin Ian King <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/clocksource/bcm2835_timer.c

···
 	ret = setup_irq(irq, &timer->act);
 	if (ret) {
 		pr_err("Can't set up timer IRQ\n");
-		goto err_iounmap;
+		goto err_timer_free;
 	}
 
 	clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
···
 	pr_info("bcm2835: system timer (irq = %d)\n", irq);
 
 	return 0;
+
+err_timer_free:
+	kfree(timer);
 
 err_iounmap:
 	iounmap(base);