iwlwifi: pcie: fix the use of a wrong define

The code checks that we haven't exceeded the maximum number of
TBs by comparing to a define of gen1 instead of gen2, fix it.
Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/tx-gen2.c

@@ -216,7 +216,7 @@ static int iwl_pcie_gen2_set_tb(struct iwl_trans *trans,
 	int idx = iwl_pcie_gen2_get_num_tbs(trans, tfd);
 	struct iwl_tfh_tb *tb;
 
-	if (WARN_ON(idx >= IWL_NUM_OF_TBS))
+	if (WARN_ON(idx >= IWL_TFH_NUM_TBS))
 		return -EINVAL;
 	tb = &tfd->tbs[idx];