gpio: mcp23s08: Do not free unrequested interrupt

If devm_request_threaded_irq fails for some reason we call
mcp23s08_irq_teardown afterwards.
Do not free the unrequested interrupt in this case. free_irq can also be
omitted for the error free case because we use devm_request_threaded_irq.

Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-mcp23s08.c

@@ -514,8 +514,6 @@ static void mcp23s08_irq_teardown(struct mcp23s08 *mcp)
 {
 	unsigned int irq, i;
 
-	free_irq(mcp->irq, mcp);
-
 	for (i = 0; i < mcp->chip.ngpio; i++) {
 		irq = irq_find_mapping(mcp->irq_domain, i);
 		if (irq > 0)