mfd: menelaus: Remove obsolete local_irq_disable() and local_irq_enable()

Since

commit e6229bec ("rtc: make rtc_update_irq callable with irqs enabled")

rtc_update_irq() is callable with irqs enabled, see the rtc drivers.
So update this accordingly.

Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
Acked-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Signed-off-by: Lee Jones <lee.jones@linaro.org>