mfd: ab8500: Use irqdomain to map interrupts

All subdrivers use the irqdomain to demux AB8500 IRQs but here
in the hierarchical path we find a leftover instance using the
hard-coded IRQ base. Convert it to use irqdomain with a
oneliner.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/ab8500-core.c

@@ -491,7 +491,7 @@ static int ab8500_handle_hierarchical_line(struct ab8500 *ab8500,
 		if (line == AB8540_INT_GPIO43F || line == AB8540_INT_GPIO44F)
 			line += 1;
 
-		handle_nested_irq(ab8500->irq_base + line);
+		handle_nested_irq(irq_create_mapping(ab8500->domain, line));
 	}
 
 	return 0;