mac80211: add association capabilty and timing info into bss_conf

This patch adds assocation capability, timestamp (tsf) and beacon interval
to bss_conf. This is required for successful assocation of iwlwifi drivers

Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>