rtc: ds1343: cleanup .remove

It is not necessary to call device_init_wakeup(dev, false) in .remove as
device_del will take care of that. It is also not necessary to
devm_free_irq. Finally, dev_pm_clear_wake_irq can be called
unconditionally.

Link: https://lore.kernel.org/r/20191019204941.6203-9-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>