orinoco: replace function ieee80211_{dsss_chan_to_freq, freq_to_dsss_chan}

Replace ieee80211_{dsss_chan_to_freq, freq_to_dsss_chan} with more
generic ieee80211_{channel_to_frequency, frequency_to_channel}.

File <net/cfg80211.h> has already been included. It's safe to use
IEEE80211_BAND_2GHZ here.

This change is a preparation for the removal of function
ieee80211_{dsss_chan_to_freq, freq_to_dsss_chan}.

Signed-off-by: Zhao, Gang <gamerh2o@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/orinoco/hw.c

@@ -1193,7 +1193,7 @@ int orinoco_hw_get_freq(struct orinoco_private *priv)
 		goto out;
 
 	}
-	freq = ieee80211_dsss_chan_to_freq(channel);
+	freq = ieee80211_channel_to_frequency(channel, IEEE80211_BAND_2GHZ);
 
  out:
 	orinoco_unlock(priv, &flags);