iwlwifi: dvm: scan: Demote a few nonconformant kernel-doc headers

iwlwifi: dvm: scan: Demote a few nonconformant kernel-doc headers

2 of which do not attempt to document their parameters, 1 does a poor job.

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

 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:193: warning: Function parameter or member 'priv' not described in 'iwl_scan_cancel'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:205: warning: Function parameter or member 'priv' not described in 'iwl_scan_cancel_timeout'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'frame' not described in 'iwl_fill_probe_req'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'ta' not described in 'iwl_fill_probe_req'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'ies' not described in 'iwl_fill_probe_req'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'ie_len' not described in 'iwl_fill_probe_req'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'ssid' not described in 'iwl_fill_probe_req'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'ssid_len' not described in 'iwl_fill_probe_req'
 drivers/net/wireless/intel/iwlwifi/dvm/scan.c:570: warning: Function parameter or member 'left' not described in 'iwl_fill_probe_req'

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/20200910065431.657636-12-lee.jones@linaro.org