iwlwifi: perform bss_info_changed post association work right away

Do not use workqueue for bss_info_changed post association work.
When driver is notified of association the upper layer will be notified
right after that the association is complete. Doing the post association
work in a workqueue introduces a race condition where the upper layer may
want to make use of the association, but it is not yet complete.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
Acked-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>