ASoC: wcd9335: Fix digital power collapse when XO shutdown

When XO shutdown happens, workqueue scheduled for digital
power collapse is not triggered. In tasha suspend, put
digital core in power collapse if workqueue is pending.

Change-Id: I4ae9bad6b18dd54217fcad5ad60673ee726f4700
Signed-off-by: Laxminath Kasam <lkasam@codeaurora.org>