ASoC: dapm: Expose snd_soc_dapm_new_control_unlocked properly

We use snd_soc_dapm_new_control_unlocked for topology and have local
declaration, instead declare it properly in header like already declared
snd_soc_dapm_new_control.

Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@intel.com>
Link: https://lore.kernel.org/r/20190827141712.21015-4-amadeuszx.slawinski@linux.intel.com
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>