wlan: Use power save mode as DHCP start/stop indication.

Current Android framework always sends power save mode to false when
starting DHCP and vice versa when DHCP session ends. Replaced driver
usage of BTCOEXMODE as the DHCP start/stop indication to power save
mode setting.

Change-Id: I90a7e0eb45b484cd81904e0d56af383003974cf2
CRs-Fixed: 679366
diff --git a/CORE/HDD/src/wlan_hdd_cfg80211.c b/CORE/HDD/src/wlan_hdd_cfg80211.c
index c0fb57c..30a2c70 100644
--- a/CORE/HDD/src/wlan_hdd_cfg80211.c
+++ b/CORE/HDD/src/wlan_hdd_cfg80211.c
@@ -9405,6 +9405,25 @@
      **/
     vos_status =  wlan_hdd_enter_bmps(pAdapter, !mode);
 
+    if (!mode)
+    {
+        VOS_TRACE(VOS_MODULE_ID_HDD, VOS_TRACE_LEVEL_DEBUG,
+                  "%s: DHCP start indicated through power save", __func__);
+
+        pHddCtx->btCoexModeSet = TRUE;
+        sme_DHCPStartInd(pHddCtx->hHal, pAdapter->device_mode,
+                         pAdapter->sessionId);
+    }
+    else
+    {
+       VOS_TRACE(VOS_MODULE_ID_HDD, VOS_TRACE_LEVEL_DEBUG,
+                  "%s: DHCP stop indicated through power save", __func__);
+
+        pHddCtx->btCoexModeSet = FALSE;
+        sme_DHCPStopInd(pHddCtx->hHal, pAdapter->device_mode,
+                        pAdapter->sessionId);
+    }
+
     EXIT();
     if (VOS_STATUS_E_FAILURE == vos_status)
     {