ASoC: codecs: wcd934x: unregister clock provider during remove

mclk clock provider needs to be unregistered on driver remove so that
the driver does not fail to reload.

Fixes: a61f3b4f ("ASoC: wcd934x: add support to wcd9340/wcd9341 codec")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>