power: qcom: Add hold soc while full feature to QG driver

If hold soc while full feature is defined, hold soc at 100% till
recharge or discharge event is triggered.

Also, fix the return handling from poll-event.

CRs-Fixed: 2190528
Change-Id: I6d602622f4504af44d65bccd54582e33be6169ef
Signed-off-by: Vamshi Krishna B V <vbv@codeaurora.org>
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>