mac80211: move netif_carrier_on to after ieee80211_bss_info_change_notify

Putting netif_carrier_on before configuring the driver/device with the
new association state may cause a race (tx frames may be sent before
configuration is done)

Signed-off-by: Guy Cohen <guy.cohen@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>