tests: Fix PSOLineWidthInvalid test

Change-Id: I7ccf658a1025f1006b27a759d3432948fc198da0
diff --git a/tests/layer_validation_tests.cpp b/tests/layer_validation_tests.cpp
index 7237531..5f420f9 100644
--- a/tests/layer_validation_tests.cpp
+++ b/tests/layer_validation_tests.cpp
@@ -7924,6 +7924,7 @@
     VkPipelineRasterizationStateCreateInfo rs_ci = {};
     rs_ci.sType = VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO;
     rs_ci.pNext = nullptr;
+    rs_ci.rasterizerDiscardEnable = VK_TRUE;
 
     // Check too low (line width of -1.0f).
     rs_ci.lineWidth = -1.0f;