iwlwifi: pcie: claim ownership on the device after stop_device()

Not doing so would allow other possible users of the device
to take ownership and prevent normal WiFi operation.

This fixes the second part of:
https://bugzilla.kernel.org/show_bug.cgi?id=87191



Reviewed-by: Moshe Harel <moshe.harel@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>