wifi: ath12k: Set default beacon mode to burst mode

Currently, firmware does not like when beacon mode is set as staggered
mode for more than one beaconing vifs. Beacon mode for multiple
beaconing (transmitted) vifs are expected to be in burst mode. So set
beacon mode to burst mode by default.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0.1-00029-QCAHKSWPL_SILICONZ-1

Signed-off-by: Sidhanta Sahu <quic_sidhanta@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20230905213943.12275-1-quic_sidhanta@quicinc.com