ASoC: imx-spdif: don't print EPROBE_DEFER as error

Probe deferral is to be expected during normal operation, so avoid
printing an error when it is encountered.

Removing the goto would not be strictly necessary. However, if
code gets added later, the cleanup in the EPROBE_DEFER case likely
would get missed.

Signed-off-by: Stefan Agner <stefan@agner.ch>
Reviewed-by: Daniel Baluta <daniel.baluta@nxp.com>
Acked-by: Nicolin Chen <nicoleotsuka@gmail.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>