ASoC: tpa6130a2: Use devm_* APIs

Converted to use devm_gpio_request and devm_regulator_get APIs.
These are device managed and make error handling and cleanup
a bit simpler.

Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>