ASoC: tegra: tegra20_das: Make helper functions return void

These only ever return a value != 0 if the parameter das is NULL. In the
only caller however it's already asserted this isn't the case.

So convert the functions to return void and simplify the caller
accordingly.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20220629194224.175607-4-u.kleine-koenig@pengutronix.de


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