iwlwifi: move iwl_free_tfds_in_queue to iwlagn

This function is only used by the agn drivers,
so doesn't have to be in core and exported.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>

diff --cc drivers/net/wireless/iwlwifi/iwl-agn-lib.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-agn.h
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-core.h
Simple merge

diff --cc drivers/net/wireless/iwlwifi/iwl-tx.c
Simple merge