gpio/davinci: Avoid redundant lookup of irq_data

It's pretty silly to do

     void *cd = irq_get_chip_data(irq_data->irq);

because that results in cd = irq_data->chip_data, but goes through a
redundant lookup of the irq_data. Use irq_data directly.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: linux-gpio@vger.kernel.org