iwl3945: use iwl_rx_reply_error notification

Patch removes duplicate code from iwl3945 and uses
iwl_rx_reply_error and spectrum notifications from iwlwifi.

Signed-off-by: Abhijeet Kolekar <abhijeet.kolekar@intel.com>
Acked-by: Samuel Ortiz <samuel.ortiz@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>