iio: adc: stm32-adc: Use generic_handle_domain_irq()

The call chain
	generic_handle_irq(irq_find_mapping(domain, x));

could be replaced with
	generic_handle_domain_irq(domain, x);

which looks up the struct irq_desc for the interrupt and handles it with
handle_irq_desc().
This is a slight optimisation given that the driver invokes only one
function and the struct irq_desc is used directly instead being looked
up via irq_to_desc().

Use generic_handle_domain_irq().
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Link: https://lore.kernel.org/r/YnuYoQIzJoFIyEJY@linutronix.deSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/stm32-adc-core.c

@@ -356,7 +356,7 @@ static void stm32_adc_irq_handler(struct irq_desc *desc)
 		if ((status & priv->cfg->regs->eoc_msk[i] &&
 		     stm32_adc_eoc_enabled(priv, i)) ||
 		     (status & priv->cfg->regs->ovr_msk[i]))
-			generic_handle_irq(irq_find_mapping(priv->domain, i));
+			generic_handle_domain_irq(priv->domain, i);
 	}
 
 	chained_irq_exit(chip, desc);