The wakeup packet in the status response is padded out
to a multiple of 4 bytes by the firmware for transfer
to the host, take that into account when checking the
length of the command.

Also, the reported wakeup packet includes the FCS but
the userspace API doesn't, so remove that. If it is a
data packet it is reported as an 802.3 packet but I
forgot to take into account and remove the encryption
head/tail, fix all of that as well.
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>