iwl3965: remove useless network and duplicate checking

mac802 can handle duplicate packages on its own, so let it do it.
The patch is based on patch from Johannes Berg for iwl4965.

Signed-off-by: Adel Gadllah <adel.gadllah@gmail.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>