pinctrl: mcp23s08: fix irq setup order

When using mcp23s08 module with gpio-keys, often (50% of boots)
it fails to get irq numbers with message:
"gpio-keys keys: Unable to get irq number for GPIO 0, error -6".
Seems that irqs must be setup before devm_gpiochip_add_data().

Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Mastykin <mastichi@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>