Eliminate implicit coercion of signed literal to unsigned value

UBSAN does not like this.

Bug: 132903913
Change-Id: Id7c9d18c41754251c1da2ec43e1c47b61afa55d1
diff --git a/ipc/avb_ipc.cpp b/ipc/avb_ipc.cpp
index a219eca..86d25ef 100644
--- a/ipc/avb_ipc.cpp
+++ b/ipc/avb_ipc.cpp
@@ -292,8 +292,7 @@
         event.handle = INVALID_IPC_HANDLE;
         event.event = 0;
         event.cookie = nullptr;
-        unsigned long timeout = -1;
-        rc = wait_any(&event, timeout);
+        rc = wait_any(&event, INFINITE_TIME);
 
         if (rc == NO_ERROR) {  // got an event
             if (event.handle == port) {