[PATCH] mac80211: consolidate encryption

Currently we run through all crypto handlers for each transmitted
frame although we already know which one will be used. This
changes the code to invoke only the needed handler. It also moves
the wep code into wep.c.

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