iwlwifi: remove useless network and duplicate checking

The iwlwifi drivers go to great lengths to avoid passing packets to
mac80211 they think shouldn't go there, while mac80211 can (of course!)
handle them very well.

Especially in the case of duplicate packets this is interesting
because it's such a performance hog (especially for IBSS networks)
while mac80211 does that work on the side without much effort.

This patch removes all that and leaves only what is absolutely
necessary for the hardware.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>