soc: qcom: dfc: DFC powersave fixes

-Fixed possible data stall that could happen after APM due to
queues not being enabled.
-Removed rtnl lock so powersave will not be delayed.
-Fixed race condition to set default grant when powersave is enabled.

Change-Id: Iaef95e814c2a3dee39e1da6dd334a3439c0ccbf8
Acked-by: Weiyi Chen <weiyic@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>