drm/bridge: dw-hdmi: Fix return error path

If devm_request_threaded_irq() fails we should jump to 'err_iahb' label that
will disable the clocks that were previously enabled.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>