ath11k: Add sta debugfs support to configure ADDBA and DELBA

Add support to test aggregation procedures (addba/addba_resp/delba)
manually by adding the required callbacks in sta debugfs files.

To enable automatic aggregation in target,

    echo 0 > /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/
	     stations/XX:XX:XX:XX:XX:XX/aggr_mode

For manual mode,

    echo 1 > /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/
	     stations/XX:XX:XX:XX:XX:XX/aggr_mode

To send addba response,
    echo 0 25 > /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/
		stations/XX:XX:XX:XX:XX:XX/addba_resp

To send addba,
    echo 1 32 > /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/
		stations/XX:XX:XX:XX:XX:XX/addba

To send delba,
    echo 0 1 37 > /sys/kernel/debug/ieee80211/phyX/netdev:wlanX/
		  stations/XX:XX:XX:XX:XX:XX/delba

Signed-off-by: Maharaja Kennadyrajan <mkenna@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/1585213026-28406-1-git-send-email-mkenna@codeaurora.org