ASoC: topology: Simplify remove_widget function

ASoC: topology: Simplify remove_widget function

Now that enum and mixer kcontrols are freed by resource management
framework, removing kcontrol becomes one function call, so simplify code
in remove_widget.

Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Reviewed-by: Cezary Rojewski <cezary.rojewski@intel.com>
Link: https://lore.kernel.org/r/20201030145427.3497990-7-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>