[VOL-3548] Differentiate between OLT gRPC channel disconnect and device reboot

- Return the previously_connected state flag in response to GetDeviceInfo to VOLTHA

Change-Id: I3a39eccdda386658226c6379a4815900b808795d
diff --git a/agent/common/state.h b/agent/common/state.h
index 6092aa8..b554abf 100644
--- a/agent/common/state.h
+++ b/agent/common/state.h
@@ -28,7 +28,7 @@
         return activated;
     }
 
-    bool previsouly_connected() {
+    bool previously_connected() {
         return connected_once;
     }