mfd: ezx-pcap: Use generic_handle_irq_safe().

Instead of manually disabling interrupts before invoking use
generic_handle_irq_safe() which can be invoked with enabled and disabled
interrupts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220211181500.1856198-6-bigeasy@linutronix.de