ASoC: imx-sgtl5000: Use devm_clk_get()

Commit 9e13f345 (ASoC: sgtl5000: Let the codec acquire its clock) removed the
clk_put calls.

Let's use devm_clk_get() instead, so that we do not need to call them anymore.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>