mac80211: insert WDS peer after adding interface

This reorders the open code so that WDS peer STA info entries
are added after the corresponding interface is added to the
driver so that driver callbacks aren't invoked out of order.
Also make any master device startup fatal.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>