When the stations are being restored because of unassoc
RXON, the LQ cmd may not have been initialized because it
is initialized only after association.
Sending zeroed LQ_CMD makes the fw unhappy: it raises
SYSASSERT_2078.

Cc: stable@vger.kernel.org
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
[move zero_lq and make static const]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>