mfd: twl4030-irq: Log an error in twl4030_sih_setup if the module cannot be found

As silently failing isn't that nice, emit an error message at a place
that was silent on failure up to now.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>