gpio: set data first, then chip and handler

During irq mapping, in irq_set_chip_and_handler() the process
of setting this up may incur calls to lock the irqchip, which
in turn may need to dereference and use the chip data. So set
the data first, then set the chip and handler.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>