staging: greybus: Fix the irq API abuse

Nothing outside of low level architecture code is supposed to look up
interrupt descriptors and fiddle with them.

Replace the open coded abuse by calling generic_handle_irq().

This still does not explain why and in which context this connection
magic is injecting interrupts in the first place and why this is correct
and safe, but at least the API abuse is gone.

Fixes: 036aad9d ("greybus: gpio: add interrupt handling support")
Fixes: 2611ebef ("greybus: gpio: don't call irq-flow handler directly")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/87o8t9boqq.fsf@nanos.tec.linutronix.de


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>