mac80211: remove IBSS merge delay

This reverts 4a332a38
("mac80211: Give it some time to do the TSF sync").

There's no point in waiting with a new IBSS merge
just because the hardware hasn't merged up with
the old IBSS yet, and since 34e8f082 we no longer
attempt to merge with the IBSS we're already in.

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