iwlwifi: mvm: move TX PN assignment for TKIP to the driver

If protocol offloading is configured, the fw might generate some
frames (e.g. arp response) on its own during d3/d0i3.

On d3/d0i3 exit the driver queries the updated PN (if relevant),
and updates its keys (for the d0i3 case, this is done by
iwl_mvm_d0i3_exit_work(), which is scheduled on d0i3 exit)

While in d0i3, iwlmvm defers tx frames until d0i3 exit, and
then continues their processing.

This is problematic with TKIP, since the frame's PN has already
been set at this stage (in contrast to CCMP, where the PN is
being set only later on), so both the frame's PN and the upcoming
PN update (from d0i3 exit work) might be wrong.

Fix it by moving the TX PN assignment (for TKIP) to the driver,
similarly to CCMP.

Signed-off-by: Eliad Peller <eliadx.peller@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>