iwlwifi: rename generic iwlagn functions that had a HW specific name

This patch renames functions that are generic in iwl-agn and had a iwl4965
prefix.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Reviewed-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>