Add the support for the feature of Full Power Down while
in low power mode.
For this feature, it need to power down wlan chip when
suspend, and power up wlan chip when resume, so need to
change to call wlan driver shutdown and then power off the
wlan chip instead of calling wlan driver suspend when do
suspend, and changing to do power on wlan chip, download
wlan firmware, and calling wlan driver reinit instead of
calling wlan driver resume when do resume.
Change-Id: I293647175c151da0fd6628345f98ea65c83b1bb3
CRs-Fixed: 3061366
b43015863f