iwlwifi: mvm: don't send RFH_QUEUE_CONFIG_CMD with no queues

If we have only a single RX queue, such as when MSI-X is not
available, we should not send the RFH_QUEUEU_CONFIG_CMD, because our
only queue is the same as the command queue and will be configured as
part of the context info.  Our code was actually trying to send the
command with 0 queues, which caused UMAC assert 0x1D04.

Fix that by not sending the command when we have a single queue.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20201008180656.c35eeb3299f8.I08f79a6ebe150a7d180b7005b24504bfdba6d8b5@changeid

drivers/net/wireless/intel/iwlwifi/mvm/fw.c

@@ -133,7 +133,14 @@ static int iwl_configure_rxq(struct iwl_mvm *mvm)
 		.dataflags[0] = IWL_HCMD_DFL_NOCOPY,
 	};
 
-	/* Do not configure default queue, it is configured via context info */
+	/*
+	 * The default queue is configured via context info, so if we
+	 * have a single queue, there's nothing to do here.
+	 */
+	if (mvm->trans->num_rx_queues == 1)
+		return 0;
+
+	/* skip the default queue */
 	num_queues = mvm->trans->num_rx_queues - 1;
 
 	size = struct_size(cmd, data, num_queues);