ASoC: mchp-i2s-mcc: Fix unprepare of GCLK

If hw_free() gets called after hw_params(), GCLK remains prepared,
preventing further use of it. This patch fixes this by unpreparing the
clock in hw_free() or if hw_params() gets an error.

Fixes: 7e0cdf545a55 ("ASoC: mchp-i2s-mcc: add driver for I2SC Multi-Channel Controller")
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Link: https://lore.kernel.org/r/20190820162411.24836-2-codrin.ciubotariu@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>