ASoC: fsl_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.

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>