Some APs send management frames with junk padding after the last IE.
We already account for a similar problem with some Apple Airport
devices, but at least one device is known to send more than a single
extra byte.  The device in question is the Draytek Vigor2900:

	http://www.draytek.com.au/products/Vigor2900.php

The junk in question looks like an IE that runs off the end of the
frame.  This cause us to return ParseFailed.  Since the frame in
question is an association response, this causes us to fail to associate
with this AP.

The return code from ieee802_11_parse_elems is superfluous.
All callers still check for the presence of the specific IEs that
interest them anyway.  So, remove the return code so the parse never
"fails".
Acked-by: NMichael Wu <flamingice@sourmilk.net>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>