ASoC: kirkwood: fix IRQ error handling

Propagate the error code from request_irq(), rather than returning
-EBUSY.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Link: https://lore.kernel.org/r/E1iNIqh-0000tW-EZ@rmk-PC.armlinux.org.uk


Signed-off-by: Mark Brown <broonie@kernel.org>