iwlwifi: limit rx bufs to 2048

Recent devices are configured with 4096 RX pages that lead to an
increased memory usage. For the moment lower the amount to 2048
and treat in potientially lower throughput for more conservative
memory consumption.

diff --git src/linux/drivers/net/wireless/intel/iwlwifi/pcie/drv.c src/linux/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
index dea4d6478..f063e22c1 100644
--- src/linux/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
+++ src/linux/drivers/net/wireless/intel/iwlwifi/pcie/drv.c
@@ -1467,6 +1467,10 @@ static int iwl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 			u16_get_bits(link_status, PCI_EXP_LNKSTA_CLS);
 	}
 
+	/* limit some recent cards that use 4096 */
+	if (trans_pcie->num_rx_bufs > 2048)
+		trans_pcie->num_rx_bufs = 2048;
+
 	ret = iwl_trans_init(iwl_trans);
 	if (ret)
 		goto out_free_trans;