build: loader: Fix warnings for 32-bit linux

Change-Id: Ied7668aa7edeef01675dd4f358916d3e8bc07b27
diff --git a/loader/loader.c b/loader/loader.c
index 73281f9..30a3b2d 100644
--- a/loader/loader.c
+++ b/loader/loader.c
@@ -381,9 +381,9 @@
     va_end(ap);
 
     if (inst) {
-        util_DebugReportMessage(inst, msg_type,
-                                VK_DEBUG_REPORT_OBJECT_TYPE_INSTANCE_EXT,
-                                (uint64_t)inst, 0, msg_code, "loader", msg);
+        util_DebugReportMessage(
+            inst, msg_type, VK_DEBUG_REPORT_OBJECT_TYPE_INSTANCE_EXT,
+            (uint64_t)(uintptr_t)inst, 0, msg_code, "loader", msg);
     }
 
     if (!(msg_type & g_loader_log_msgs)) {