tests: NullRenderPass expected error message

Update VkLayerTest.NullRenderPass to expect the error message from
parameter validation in anticipation that the duplicate check in core
validation will be removed.

Change-Id: I3267d28cf8b129882e2044901ba0fc26c9ffdc21
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index 827ceff..6e6da7a 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -7958,7 +7958,7 @@
 TEST_F(VkLayerTest, NullRenderPass) {
     // Bind a NULL RenderPass
     m_errorMonitor->SetDesiredFailureMsg(VK_DEBUG_REPORT_ERROR_BIT_EXT,
-                                         "You cannot use a NULL RenderPass object in vkCmdBeginRenderPass()");
+                                         "vkCmdBeginRenderPass: required parameter pRenderPassBegin specified as NULL");
 
     ASSERT_NO_FATAL_FAILURE(InitState());
     ASSERT_NO_FATAL_FAILURE(InitRenderTarget());