mfd: tps80031: MFD_TPS80031 needs to select REGMAP_IRQ

This driver uses regmap_irq APIs, thus need to select REGMAP_IRQ.
IRQ_DOMAIN will be selected if select REGMAP_IRQ, thus remove it here.

This fixes below build errors:

drivers/built-in.o: In function `tps80031_remove':
drivers/mfd/tps80031.c:534: undefined reference to `regmap_del_irq_chip'
drivers/built-in.o: In function `tps80031_irq_init':
drivers/mfd/tps80031.c:305: undefined reference to `regmap_add_irq_chip'
drivers/built-in.o: In function `tps80031_probe':
drivers/mfd/tps80031.c:496: undefined reference to `regmap_irq_get_domain'
drivers/mfd/tps80031.c:512: undefined reference to `regmap_del_irq_chip'
make: *** [vmlinux] Error 1

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>