iwlwifi: move agn only tx functions from iwlcore to iwlagn

Identify the tx functions only used by agn driver and move those from
iwlcore to iwlagn.

Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
11 files changed