ASoC: tegra_sgtl5000: fix device_node refcounting

Similar to the following:

commit 43217236 ("ASoC: tegra_alc5632: fix device_node refcounting")

commit 7c5dfd54 ("ASoC: tegra: fix device_node refcounting")

Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>