ath10k: add debugfs support to get power save state change of STA

This patch helps to get the power save state change of each peer
connected to the AP. With WMI_10_4_PEER_STA_PS_STATECHG_EVENTID
event, ps state of each peer is reported to user space via
debugfs.

Use the below command to get the ps state of each sta:
cat /sys/kernel/debug/ieee80211/phyX/netdev::wlanX/stations/
XX:XX:XX:XX:XX:XX/peer_ps_state

If STA is in power save state, we get the peer_ps_state value as 1.
if STA is not in power save state, we get the peer_ps_state value as 0.
If ps_state event is disabled, we get the peer_ps_state value as 2.

We can enable/disable the ps_state events using the debugfs flag
"ps_state_enable"

echo Y > /sys/kernel/debug/ieee80211/phyX/ath10k/ps_state_enable

Y = 1 to enable and Y = 0 to disable

Tested in QCA4019 with firmware ver 10.4-3.2.1.1-00011

Signed-off-by: Maharaja Kennadyrajan <mkenna@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ath/ath10k/wmi.h

@@ -4161,6 +4161,13 @@ enum wmi_tpc_pream_5ghz {
 	WMI_TPC_PREAM_5GHZ_HTCUP,
 };
 
+#define	WMI_PEER_PS_STATE_DISABLED	2
+
+struct wmi_peer_sta_ps_state_chg_event {
+	struct wmi_mac_addr peer_macaddr;
+	__le32 peer_ps_state;
+} __packed;
+
 struct wmi_pdev_chanlist_update_event {
 	/* number of channels */
 	__le32 num_chan;