Fix Linux packat socket regression work around

Fix Linux packat socket regression work around

Commit e6dd8196e5daf39e4204ef8ecd26dd50fdca6040 ('Work around Linux
packet socket regression') added a mechanism to close the workaround
bridge socket in l2_packet_receive(). However, it did not take into
account the possibility of the l2->rx_callback() closing the l2_packet
socket altogether. This could result in use of freed memory when usin
RSN pre-authentication. Fix this by reordering the calls to clear the
workaround socket before calling the rx_callback.

Signed-off-by: Jouni Malinen <j@w1.fi>