ath11k: monitor mode clean up to use separate APIs

If monitor interface is enabled in co-exist mode, only local traffic are
captured. It's caused by missing monitor vdev in co-exist mode. So,
monitor mode clean up is done with separate Monitor APIs. For this,
introduce flags monitor_started and monitor_vdev_created.

Tested-on: IPQ8074 hw2.0 AHB WLAN.HK.2.4.0.1-01725-QCAHKSWPL_SILICONZ-1

Co-developed-by: Miles Hu <milehu@codeaurora.org>
Signed-off-by: Miles Hu <milehu@codeaurora.org>
Co-developed-by: Vasanthakumar Thiagarajan <vthiagar@codeaurora.org>
Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@codeaurora.org>
Signed-off-by: Seevalamuthu Mariappan <seevalam@codeaurora.org>
Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210721162053.46290-4-jouni@codeaurora.org