drm/i2c: tda998x: fix error cleanup paths

If tda998x_get_audio_ports() fails, and we requested the interrupt, we
fail to free the interrupt before returning failure.  Rework the failure
cleanup code and exit paths so that we always clean up properly after an
error, and always propagate the error code.

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>