iwlwifi: Fix 52 rate report in rx status

This patch fixes reporting rate in RX packets in 52 band.
The rate was updated from CCK rate index instead of OFDM rate 6M
Most of the patch is collateral clean up

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-4965-rs.h b/drivers/net/wireless/iwlwifi/iwl-4965-rs.h
index 13b6c72..911f213 100644
--- a/drivers/net/wireless/iwlwifi/iwl-4965-rs.h
+++ b/drivers/net/wireless/iwlwifi/iwl-4965-rs.h
@@ -259,7 +259,7 @@
 	return rate;
 }
 
-extern int iwl4965_rate_index_from_plcp(int plcp);
+extern int iwl4965_hwrate_to_plcp_idx(u32 rate_n_flags);
 
 /**
  * iwl4965_fill_rs_info - Fill an output text buffer with the rate representation