RpcServer: Don't shadow local var

Test: pass
Change-Id: Ied32f20b186f64fedfc22adf7a9038221405dce0
diff --git a/libs/binder/RpcServer.cpp b/libs/binder/RpcServer.cpp
index a8f3fa8..2a87ae4 100644
--- a/libs/binder/RpcServer.cpp
+++ b/libs/binder/RpcServer.cpp
@@ -278,7 +278,7 @@
                 return;
             }
 
-            RpcAddress sessionId = RpcAddress::zero();
+            sessionId = RpcAddress::zero();
             size_t tries = 0;
             do {
                 // don't block if there is some entropy issue