ath10k: don't set cck/ofdm scan flags

mac80211 already does provide complete IEs for
Probe Requests for hw scan and ath10k firmware was
appending duplicate Supported Rates IEs
unnecessarily.

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