power: qpnp-smbcharger: hold the device awake during parallel taper

During the parallel charging's taper charge algorithm, hold the device
awake so that I2C transactions do not timeout due to suspend.

CRs-Fixed: 878738
Change-Id: I0a4d891c458e88f2678983e9ae185b52cdd18973
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>