ASoC: tegra: Read and use the GPIO flags of the headphone detect

The headphone detect was hardcoded to low-active, use the flags from
DT to allow high-active as well.

Signed-off-by: Alban Bedel <alban.bedel@avionic-design.de>
Acked-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@kernel.org>