DISPATCH-2344: Fixes #473 - Reduced the severity of "unknown router" logs from ERROR to WARNING.

(cherry picked from commit cd616e792a142d7b016fe6440d19ac37d728fe1f)
diff --git a/src/router_core/modules/mobile_sync/mobile.c b/src/router_core/modules/mobile_sync/mobile.c
index fe65284..5a856af 100644
--- a/src/router_core/modules/mobile_sync/mobile.c
+++ b/src/router_core/modules/mobile_sync/mobile.c
@@ -91,7 +91,7 @@
     // There is a possibility here that router_id is null but that is fine. We want to print it out either way
     // which will help us in debugging.
     //
-    qd_log(msync->log, QD_LOG_ERROR, "Received %s from an unknown router with router id %s", opcode, r_id);
+    qd_log(msync->log, QD_LOG_WARNING, "Received %s from an unknown router with router id %s", opcode, r_id);
     free(r_id);
 }