wireless: fix several minor description typos

Signed-off-by: Walter Goldens <goldenstranger@yahoo.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h
index b44a2e5..049e507 100644
--- a/include/net/cfg80211.h
+++ b/include/net/cfg80211.h
@@ -89,7 +89,7 @@
  * @max_power: maximum transmission power (in dBm)
  * @beacon_found: helper to regulatory code to indicate when a beacon
  *	has been found on this channel. Use regulatory_hint_found_beacon()
- *	to enable this, this is is useful only on 5 GHz band.
+ *	to enable this, this is useful only on 5 GHz band.
  * @orig_mag: internal use
  * @orig_mpwr: internal use
  */