iwlagn: add dumpit support for testmode trace function

For testmode trace function, huge amout of data need to pass to userspace.
Use the build-in nl80211 dumpt it function

Require nl80211 testmode dumpit support patch.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-agn.c b/drivers/net/wireless/iwlwifi/iwl-agn.c
index 099c279..6f1edb4 100644
--- a/drivers/net/wireless/iwlwifi/iwl-agn.c
+++ b/drivers/net/wireless/iwlwifi/iwl-agn.c
@@ -3352,6 +3352,7 @@
 	.offchannel_tx = iwl_mac_offchannel_tx,
 	.offchannel_tx_cancel_wait = iwl_mac_offchannel_tx_cancel_wait,
 	CFG80211_TESTMODE_CMD(iwl_testmode_cmd)
+	CFG80211_TESTMODE_DUMP(iwl_testmode_dump)
 };
 
 static u32 iwl_hw_detect(struct iwl_priv *priv)