qcacld-3.0: Avoid failing driver when cesium_nl_sock failed

qcacld-2.0 to qcacld-3.0 propagation

In the dual wifi instances, the 2nd cesium_nl_sock initialization
will fail due to the first driver has registered the socket.

This doesn't have to fail the driver to be up running, so simply
print a warning in this case.

Also add a check in the case to use the cesium_nl_sock to make sure
it is properly used only when it is initialized.

Change-Id: Ia62d606c1400b437f08c28951d6a6a77428f73b1
CRs-fixed: 995038
diff --git a/core/hdd/src/wlan_hdd_main.c b/core/hdd/src/wlan_hdd_main.c
index bf2f428..5abe7ce 100644
--- a/core/hdd/src/wlan_hdd_main.c
+++ b/core/hdd/src/wlan_hdd_main.c
@@ -3935,10 +3935,8 @@
 	}
 
 	ret = hdd_open_cesium_nl_sock();
-	if (ret) {
-		hdd_alert("hdd_open_cesium_nl_sock failed");
-		goto err_ptt_deactivate;
-	}
+	if (ret)
+		hdd_warn("hdd_open_cesium_nl_sock failed");
 
 	ret = cnss_diag_activate_service();
 	if (ret) {
@@ -3950,7 +3948,6 @@
 
 err_close_cesium:
 	hdd_close_cesium_nl_sock();
-err_ptt_deactivate:
 	ptt_sock_deactivate_svc();
 err_nl_srv:
 	nl_srv_exit();