wlcore: save seq num only between recoveries

We want to seq num (freed_pkts) to initialize
on each new connection, but keep persistent
between recoveries/suspends.

Save the freed_pkts in the private block of the
sta struct (we already do a similar thing for
AP's stations).

However, keep the old wlvif->total_freed_pkts
in order to avoid major change.

TODO: clean it up.

Signed-off-by: Eliad Peller <eliad@wizery.com>
wlcore: user smaller sqn padding for GEM

On recovery, we increase the current seq num by
WL1271_TX_SQN_POST_RECOVERY_PADDING in order compensate
on packets we might have missed during recovery.

It seems that some GEM APs have issues when the
gap is too big, so use a smaller padding in this case.

Signed-off-by: Eliad Peller <eliad@wizery.com>