iwlwifi: pcie: support 2k rx buffers

The smallest rb size supported today is 4k rx buffers.
22560 devices use 2k rxb's, so allow using 2k buffers.

Signed-off-by: Golan Ben Ami <golan.ben.ami@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
index 5d9b930..d966262 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/ops.c
@@ -704,7 +704,10 @@ iwl_op_mode_mvm_start(struct iwl_trans *trans, const struct iwl_cfg *cfg,
 	}
 
 	/* the hardware splits the A-MSDU */
-	if (mvm->cfg->mq_rx_supported)
+	if (mvm->trans->cfg->device_family >=
+	    IWL_DEVICE_FAMILY_22560)
+		trans_cfg.rx_buf_size = IWL_AMSDU_2K;
+	else if (mvm->cfg->mq_rx_supported)
 		trans_cfg.rx_buf_size = IWL_AMSDU_4K;
 
 	trans->wide_cmd_header = true;