iwlwifi: pcie: fix erroneous return value

The iwl_trans_pcie_start_fw() function may return the positive value EIO
instead of -EIO in case of error.
Signed-off-by: Anton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

drivers/net/wireless/intel/iwlwifi/pcie/trans.c

@@ -1168,7 +1168,7 @@ static int iwl_trans_pcie_start_fw(struct iwl_trans *trans,
 	if (trans_pcie->is_down) {
 		IWL_WARN(trans,
 			 "Can't start_fw since the HW hasn't been started\n");
-		ret = EIO;
+		ret = -EIO;
 		goto out;
 	}