iwl-4965: test below 0 on unsigned num_tbs

num_tbs is unsigned so the test doesn't work.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwlwifi/iwl-tx.c

@@ -126,7 +126,7 @@ int iwl_hw_txq_attach_buf_to_tfd(struct iwl_priv *priv, void *ptr,
 	u32 num_tbs = IWL_GET_BITS(*tfd, num_tbs);
 
 	/* Each TFD can point to a maximum 20 Tx buffers */
-	if ((num_tbs >= MAX_NUM_OF_TBS) || (num_tbs < 0)) {
+	if (num_tbs >= MAX_NUM_OF_TBS) {
 		IWL_ERROR("Error can not send more than %d chunks\n",
 			  MAX_NUM_OF_TBS);
 		return -EINVAL;