When we enter D0i3, we must stop TXing otherwise the
sequence number we use might conflict with the firmware's
internal TX. In order to do so, we have
IWL_MVM_STATUS_IN_D0I3 which should prevent any Tx while we
enter D0i3. There is a bug in this code since we may Tx even
if IWL_MVM_STATUS_IN_D0I3 is set. This can happen as long as
mvm->d0i3_ap_sta_id is not set.

To make sure that we don't have any packet in the Tx path
while we set mvm->d0i3_ap_sta_id, call synchronize_net only
after we already set mvm->d0i3_ap_sta_id.
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>