Incorrect RSSI value in onlost/onfound

Fix for signed value in onlost/onfound

Bug: 19891550
Change-Id: Idee4c566fe0d6f10a87c92f5bf03743fddbe2261
diff --git a/include/hardware/bt_common_types.h b/include/hardware/bt_common_types.h
index f1e0984..e30ac24 100644
--- a/include/hardware/bt_common_types.h
+++ b/include/hardware/bt_common_types.h
@@ -32,7 +32,7 @@
     uint8_t  advertiser_info_present;
     uint8_t  addr_type;
     uint8_t  tx_power;
-    uint8_t  rssi_value;
+    int8_t  rssi_value;
     uint16_t time_stamp;
     bt_bdaddr_t bd_addr;
     uint8_t  adv_pkt_len;