mwifiex: reset interrupt status across device reset

When resetting the device, we might have queued up interrupts that
didn't get a chance to finish processing. We really don't need to handle
them at this point; we just want to make sure they don't cause us to try
to process old commands from before the device was reset.

Signed-off-by: Brian Norris <briannorris@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>