iwlwifi: emliminate iwl3945_mac_get_stats mac80211 handler

This patch removes empty iwl3945_mac_get_stats mac80211 handler.

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>