iwlwifi: change rate number to a constant

This patch moves a number to an understandable define
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Ron Rindjunsky <ron.rindjunsky@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl4965-base.c

@@ -5450,7 +5450,8 @@ static void iwl4965_init_hw_rates(struct iwl4965_priv *priv,
 			/*
 			 * If CCK != 1M then set short preamble rate flag.
 			 */
-			rates[i].flags |= (iwl4965_rates[i].plcp == 10) ?
+			rates[i].flags |=
+				(iwl4965_rates[i].plcp == IWL_RATE_1M_PLCP) ?
 					0 : IEEE80211_RATE_SHORT_PREAMBLE;
 		}
 	}