previous_ap and last_assoc_req were not really used for anything
meaninful, so get rid of them to reduce the size of per-STA memory
allocation.
Signed-off-by: Jouni Malinen <j@w1.fi>
Doxygen and some build tools may get a bit confused about same file
name being used in different directories. Clean this up a bit by
renaming some of the duplicated file names in src/ap.