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.

Signed-off-by: Maya Erez <qca_merez@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>