wlan: Clean up WD thread to avoid crash.

In function VosWDThread() we check if resetinprogress
is set in WD context but still execute WLAN re-init
which causes system to crash.
Clean up WD thread so that it doesnot execute WLAN
re-init when it is not shutdown.

Change-Id: Ica0ab74e98f2153dcab91e9aa111bc6dacc6e9ba
CRs-Fixed: 682616