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>
diff --git a/drivers/net/wireless/orinoco/wext.c b/drivers/net/wireless/orinoco/wext.c
index 3b5508f..b7a867b 100644
--- a/drivers/net/wireless/orinoco/wext.c
+++ b/drivers/net/wireless/orinoco/wext.c
@@ -444,7 +444,7 @@
 		for (i = 0; i < (6 - frq->e); i++)
 			denom *= 10;
 
-		chan = ieee80211_freq_to_dsss_chan(frq->m / denom);
+		chan = ieee80211_frequency_to_channel(frq->m / denom);
 	}
 
 	if ((chan < 1) || (chan > NUM_CHANNELS) ||