iwlwifi: 4965 unify rate scale variable names for station data

1, This patch renames iwl4965_rate_scale_priv to iwl4965_lq_sta.
   This type represents a station's link quality.
2. The names of the variables of this type were rs_priv, lq_data, lq, crl
   across the file. All are now unified under the name lq_sta.
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>