mfd: rt5033: MFD_RT5033 needs to select REGMAP_IRQ

Since commit 0b271258(linux-next.git) this driver uses regmap_irq and so needs
to select REGMAP_IRQ.

This fixes the following compilation errors:
ERROR: "regmap_irq_get_domain" [drivers/mfd/rt5033.ko] undefined!
ERROR: "regmap_add_irq_chip" [drivers/mfd/rt5033.ko] undefined!

Signed-off-by: Artem Savkov <asavkov@redhat.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>