ASoC: Add locking in DAPM widget power update

While playback and capture is done concurrently the dapm widget
data is accessed parallelly which results in data corruption and
kernel panic. Fix this problem by serializing the stream event
operation by adding lock

dapm_seq_run will invoke dapm power sequence for pre-sorted list
of widgets to be powered up. Kernel panic issue is observed
during stability runs with the above sequence caused by null
pointer dereference in dapm_seq_run_coalesced. Fix kernel panic
issue by checking for valid snd_soc_dapm_context pointer in
dapm_seq_run before invoking dapm_seq_run_coalesced

Widget list in dapm is getting corrupted during concurrent
use cases where dapm_power_widget is accessed. This corruption
is resulting in kernel crash in dapm. Fix the issue by adding
protection in dapm_power_widgets API.

Change-Id: I49d19860277726cf3152e104ab40627fd56c021c
CRs-Fixed: 388785
Signed-off-by: Sriranjan Srikantam <cssrika@codeaurora.org>
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>

Conflicts:

	include/sound/soc.h