iwlwifi: 3945 drop usage of union tsf

This patch replaces union tsf with u64
This also allows to use iwl_error_res
and iwl_rxon_time_cmd instead of 3945 structures

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Acked-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>