mac80211: Initialize RX's last received sequence number

The STA may drop the very first frame if it happens to be a retried
frame. This is because we maintian the last received sequence number
per TID for QoS frames and it is initialized to zero through kzalloc
during sta_info_alloc and the sequence number of the very first date
frame received would be ZERO (as per IEEE 802.11-2007, 7.1.3.4.1).

If the frame dropped happens to be an EAP Request Identity(very first
frame from the AP), then wpa_supplicnat disconnects the STA and the
whole procedure starts again.

Signed-off-by: Senthil Balasubramanian <senthilkumar@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>