staging: wilc1000: Remove unnecessary array index check

This statment triggers GCC's -Wtype-limit since key_index is an
unsigned integer so it cannot be less than zero.

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_wfi_cfgoperations.c

@@ -1054,7 +1054,7 @@ static int del_key(struct wiphy *wiphy, struct net_device *netdev,
 		}
 	}
 
-	if (key_index >= 0 && key_index <= 3 && priv->wep_key_len[key_index]) {
+	if (key_index <= 3 && priv->wep_key_len[key_index]) {
 		memset(priv->wep_key[key_index], 0,
 		       priv->wep_key_len[key_index]);
 		priv->wep_key_len[key_index] = 0;