ath10k: advertise support for AP mode channel width changes

This will enable AP mode to change channel width dynamically
based on 20/40 intolerance report sent by associated client.

Signed-off-by: Rajkumar Manoharan <rmanohar@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>