mka: Do not ignore MKPDU parameter set decoding failures

mka: Do not ignore MKPDU parameter set decoding failures

The status values returned by mka_param_body_handler.body_rx functions
are currently ignored by ieee802_1x_kay_decode_mkpdu(). If a failure is
detected the KaY should (a) stop processing the MKDPU and (b) do not
update the associated peer's liveliness.

IEEE Std 802.1X-2010, Table 11-7 (MKPDU parameter sets) and 11.11.3
(Encoding MKPDUs) dictate that MKA_SAK_USE (set type 3) will always be
encoded before MKA_DISTRIBUTED_SAK (set type 4) in MKPDUs. Due to
implementation of mka_param_body_handler, the code will always decode
MKA_SAK_USE before MKA_DISTRIBUTED_SAK. When MKA_DISTRUBUTED_SAK
contains a new SAK the code should decode MKA_DISTRUBUTED_SAK first so
that the latest SAK is in known before decoding MKA_SAK_USE.

The ideal solution would be to make two passes at MKDPU decoding: the
first pass decodes MKA_DISTRIBUTED_SAK, the second pass decodes all
other parameter sets.

A simpler and less risky solution is presented here: ignore MKA_SAK_USE
failures if MKA_DISTRIBUTED_SAK is also present. The new SAK will be
saved so that the next MKPDU's MKA_SAK_USE can be properly decoded. This
is basically what the code prior to this commit was doing (by ignoring
all errors).

Also, the only real recourse the KaY has when detecting any bad
parameter set is to ignore the MKPDU by not updating the corresponding
peer's liveliness timer, 'peer->expire'.

Signed-off-by: Michael Siedzik <msiedzik@extremenetworks.com>