pinctrl: single: Delete an unnecessary return statement in pcs_irq_chain_handler()

The script "checkpatch.pl" pointed information out like the following.

WARNING: void function return statements are not generally useful

Thus remove such a statement in the affected function.
Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-single.c

@@ -1459,8 +1459,6 @@ static void pcs_irq_chain_handler(struct irq_desc *desc)
 	pcs_irq_handle(pcs_soc);
 	/* REVISIT: export and add handle_bad_irq(irq, desc)? */
 	chained_irq_exit(chip, desc);
-
-	return;
 }
 
 static int pcs_irqdomain_map(struct irq_domain *d, unsigned int irq,