This patch fixes beacon frame sequence number generation. The code
didn't set a sequence number; it didn't show up earlier because the
hardware most people use for hostap (ie, AR5212 series stuff) sets the
sequence numbers up in hardware. Later hardware (AR5416, etc) which
can do 11n and aggregation require sequence numbers to be generated in
software.

Submitted by: paradyse@gmail.com
Approved by: re (kib)