ASoC: codecs: rt5682: initialize mutex before using

In rt5682 codec driver, a mutex called "calibrate_mutex" is used
in rt5682_calibrate() before initialization, which causes warning
in lock debug. Move the initialization before the usage of mutex.

Signed-off-by: Xun Zhang <xun2.zhang@intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>