ASoC: tegra20-spdif: remove "default m"

Make tegra20-spdif default to N as all other drivers do.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Fixes: 774fec33 ("ASoC: Tegra: Implement SPDIF CPU DAI")
Link: https://lore.kernel.org/r/8756eb5aac561173aa222c9cb64dd314ab1b1f9b.1603925200.git.mirq-linux@rere.qmqm.pl


Signed-off-by: Mark Brown <broonie@kernel.org>