ASoC: dapm: fix race condition in dapm

Dirty widget list can be accessed by multiple paths
in dapm framework. Dirty list is protected by dapm mutex.
Since dapm_set_pin and dapm_force_enable_pin function
accesses the dirty list, protect it using the dapm mutex.

CRs-Fixed: 637323
Change-Id: I8c265072083e142c0858b6cc7a983d07e7d75af0
Signed-off-by: Aviral Gupta <aviralg@codeaurora.org>