ath10k: don't use reassoc flag

Firmware actually re-creates peer entry when
reassoc flag is set. This is undesired and could
cause trouble with IBSS crypto-wise. This is also
important for upcomming bitrate mask improvement.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>