iwlwifi: configure_filter rewrite

The patch rewrites the mac80211 configure_filter handler to better mapping
mac80211 filter flags to iwlwifi hardware filter flags. We now can support
5 mac80211 filter flags: FIF_OTHER_BSS, FIF_ALLMULTI, FIF_PROMISC_IN_BSS,
FIF_BCN_PRBRESP_PROMISC and FIF_CONTROL. This patch also avoids reconnecting
if the filter flags are changed when the STA is associated. Because rx_assoc
is used when full rxon is not necessary.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>