wlan: Add callback handler for wlan suspend

Currently control reaches to caller after posting a message to WDA
in wlan suspend. In some cases it may be possible that message is
still in processing and system goes to sleep since hdd will return
due to non blocking call.

Add callback API to wait in hdd until message is posted to smd.

Change-Id: Ibd1cf138d683037a56c14b8b390d44a9a6b8803e
CRs-Fixed: 1106499
diff --git a/CORE/HDD/inc/wlan_hdd_main.h b/CORE/HDD/inc/wlan_hdd_main.h
index e52d7ae..00d5e77 100644
--- a/CORE/HDD/inc/wlan_hdd_main.h
+++ b/CORE/HDD/inc/wlan_hdd_main.h
@@ -1113,6 +1113,9 @@
    struct completion ibss_peer_info_comp;
 #endif /* WLAN_FEATURE_RMC */
 
+   /* completion variable for wlan suspend */
+   struct completion wlan_suspend_comp_var;
+
    /* Track whether the linkup handling is needed  */
    v_BOOL_t isLinkUpSvcNeeded;