staging: greybus: gpio: 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>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Johan Hovold <johan@kernel.org>
Cc: Alex Elder <elder@kernel.org>
Cc: Rui Miguel Silva <rmfrfs@gmail.com>
Link: https://lore.kernel.org/r/20220211181500.1856198-8-bigeasy@linutronix.de