qcacmn: Update rssi only when its valid

Peer stats struct members initial value 0, so when other functions call
to update peer stats have 0 rssi value which updates mininum
rssi since its the least value. So initialize the rssi with invalid
value initially

Change-Id: Ife033598c7ac47a9a26595f97bff058570d3e91f
CRs-Fixed: 2403735
diff --git a/dp/wifi3.0/dp_rx_mon_status.c b/dp/wifi3.0/dp_rx_mon_status.c
index 569a61b..43bc7a2 100644
--- a/dp/wifi3.0/dp_rx_mon_status.c
+++ b/dp/wifi3.0/dp_rx_mon_status.c
@@ -220,7 +220,7 @@
 		return;
 
 	DP_STATS_UPD(peer, rx.rssi, ppdu->rssi);
-	if (!peer->stats.rx.avg_rssi)
+	if (peer->stats.rx.avg_rssi == INVALID_RSSI)
 		peer->stats.rx.avg_rssi = ppdu->rssi;
 	else
 		peer->stats.rx.avg_rssi =