iwlwifi: mvm: fix merge damage in iwl_mvm_rx_mpdu_mq()

A call to iwl_mvm_add_rtap_sniffer_config() was missing due to a merge
damage when I submitted the patch mentioned below.  And this causes
the following compilation warning:

drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c:195:13: warning: 'iwl_mvm_add_rtap_sniffer_config' defined but not used [-Wunused-function]
 static void iwl_mvm_add_rtap_sniffer_config(struct iwl_mvm *mvm,
             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Fix it by adding the if block that calls this function.

Fixes: 9bf13bee ("iwlwifi: mvm: include configured sniffer AID in radiotap")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>