ipw2x00: comment typo fix encryptiong to encryption

The below patch fixes a typo.
Signed-off-by: Justin P. Mattock <justinmattock@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/net/wireless/ipw2x00/libipw_tx.c

@@ -395,7 +395,7 @@ netdev_tx_t libipw_xmit(struct sk_buff *skb, struct net_device *dev)
 		    (CFG_LIBIPW_COMPUTE_FCS | CFG_LIBIPW_RESERVE_FCS))
 			bytes_per_frag -= LIBIPW_FCS_LEN;
 
-		/* Each fragment may need to have room for encryptiong
+		/* Each fragment may need to have room for encryption
 		 * pre/postfix */
 		if (host_encrypt)
 			bytes_per_frag -= crypt->ops->extra_mpdu_prefix_len +