wil6210: prevent parallel suspend and dump collection

Suspend and crash dump operations can happen simultaneously
in case there is a FW assert during the suspend procedure
or when SSR calls all the devices crashdump callbacks.

To prevent that, a new flag is added, indicating that the
dumps collection is in progress, in order to allow the
suspend/reset decline if the dumps collection already started.

Change-Id: Id38d8a2f833dd692ffdc8138f0ac88fe8b6f24e2
Signed-off-by: Maya Erez <merez@codeaurora.org>