iwlwifi: mvm: tx: Demote misuse of kernel-doc headers

iwlwifi: mvm: tx: Demote misuse of kernel-doc headers

Fixes the following W=1 kernel build warning(s):

 drivers/net/wireless/intel/iwlwifi/mvm/tx.c:1379: warning: Function parameter or member 'rate_n_flags' not described in 'iwl_mvm_hwrate_to_tx_status'
 drivers/net/wireless/intel/iwlwifi/mvm/tx.c:1379: warning: Function parameter or member 'info' not described in 'iwl_mvm_hwrate_to_tx_status'
 drivers/net/wireless/intel/iwlwifi/mvm/tx.c:1431: warning: Function parameter or member 'mvm' not described in 'iwl_mvm_get_scd_ssn'

Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Intel Linux Wireless <linuxwifi@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200910065431.657636-14-lee.jones@linaro.org