mfd: ucb1x00: Prepare ucb1x00_irq for irq argument removal

irq is incremented for no value in the for loop. Remove it.

Search and update was done with coccinelle and the invaluable help of
Julia Lawall.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>